Hi there - thanks for letting me join. I’ve kept White Cloud minnows for many years indoors and I keep Koi in a large pond outdoors. 6 months ago I started to keep cherry barbs in a new bio orb. They settled really well and I change the water regularly. In the last couple of days one of the fish has started “resting” in one of the tank plants (they aren’t live plants) - it does swim around but keeps going back into the plant. No scales raised and no swollen tummy so I don’t think it’s swim bladder - feeding ok and I’ve tested the water - everything in tolerance except that the water is hard - however for the last 6 months this hasn’t bothered them. Does anyone have any suggestions please? Thankyou
Cherry barb acting strange.
- Thread starter Adana
- Start date
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Colin_T
Aquarium Advice Addict
Hi and welcome to the forum 
Can you post a video of the fish swimming, eating and resting and show the interaction between it and the other fish in the tank?
You can upload videos to YouTube, then copy & paste the link here.
If you use a mobile phone to film the fish, hold the phone horizontally so the footage fills the entire screen.
Have you added anything to the tank in the 2 weeks before this started?
What other fish, shrimp, snails are in the tank?
How often do you do water changes and how much do you change?
Do you gravel clean the substrate when you do a water change?
Do you dechlorinate the new water before adding it to the tank?
What is the ammonia, nitrite & nitrate of the water (in numbers)?
What sort of filter is in/ on the tank?
How often and how do you clean the filter?
--------------------
What is the GH (general hardness), KH (carbonate hardness) and pH of your water supply?
This information can usually be obtained from your water supply company's website or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).
Hard water generally doesn't affect soft water fishes quickly. The minerals in the hard water gradually build up in the fish's organs and slowly reduce the organs ability to function correctly. A lot of soft water fish can live in hard water for several years before they show any symptoms and by the time they do show symptoms, it's too late.
Can you post a video of the fish swimming, eating and resting and show the interaction between it and the other fish in the tank?
You can upload videos to YouTube, then copy & paste the link here.
If you use a mobile phone to film the fish, hold the phone horizontally so the footage fills the entire screen.
Have you added anything to the tank in the 2 weeks before this started?
What other fish, shrimp, snails are in the tank?
How often do you do water changes and how much do you change?
Do you gravel clean the substrate when you do a water change?
Do you dechlorinate the new water before adding it to the tank?
What is the ammonia, nitrite & nitrate of the water (in numbers)?
What sort of filter is in/ on the tank?
How often and how do you clean the filter?
--------------------
What is the GH (general hardness), KH (carbonate hardness) and pH of your water supply?
This information can usually be obtained from your water supply company's website or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).
Hard water generally doesn't affect soft water fishes quickly. The minerals in the hard water gradually build up in the fish's organs and slowly reduce the organs ability to function correctly. A lot of soft water fish can live in hard water for several years before they show any symptoms and by the time they do show symptoms, it's too late.
Hi there - thankyou so much for taking the time and trouble to reply so comprehensively. I’ve attached[three links which hopefully show the fish’s behaviour.
In answer to your questions - nothing added but I did a water change of 50%. 2 weeks ago
There are 3 other Cherry barbs and they have always been together.
I change the water every six weeks usually replacing a third of the water. I fit a new bio orb filter every six weeks - it’s a sealed unit that you fix at the base of the filter tube.
I don’t clean the gravel substrate usually but will start doing this.
I always dechlorinate the water I introduce.
The strip tests I do include the following: nitrate x 2 measures, total hardness, carbonate, chlorine and ph.
Measurements are: hardness 300 (gh) mg/l
Nitrate 50 NO2/mg1
Nitrate 0 NO3/mg1
Carbonate 80 KH/mo/1
Cl 0
Ph 7.2
The fish is swimming freely and interacting but regularly retuning to the plant which was thoroughly cleaned when I did the last water change 2 weeks ago
Hope you can help
Thankyou
Adana
https://youtu.be/g9ienoxPnpk
https://youtu.be/bv5V9dkJ68A
https://youtu.be/oeJS5rdgeMY
In answer to your questions - nothing added but I did a water change of 50%. 2 weeks ago
There are 3 other Cherry barbs and they have always been together.
I change the water every six weeks usually replacing a third of the water. I fit a new bio orb filter every six weeks - it’s a sealed unit that you fix at the base of the filter tube.
I don’t clean the gravel substrate usually but will start doing this.
I always dechlorinate the water I introduce.
The strip tests I do include the following: nitrate x 2 measures, total hardness, carbonate, chlorine and ph.
Measurements are: hardness 300 (gh) mg/l
Nitrate 50 NO2/mg1
Nitrate 0 NO3/mg1
Carbonate 80 KH/mo/1
Cl 0
Ph 7.2
The fish is swimming freely and interacting but regularly retuning to the plant which was thoroughly cleaned when I did the last water change 2 weeks ago
Hope you can help
Thankyou
Adana
https://youtu.be/g9ienoxPnpk
https://youtu.be/bv5V9dkJ68A
https://youtu.be/oeJS5rdgeMY
Last edited by a moderator:
Cherry barbs are social fish, and 4 fish isn't really enough fish for them to feel comfortable. When kept in too small a group this can stress the fish and stress will come out in various symptoms. It could be aggression directed towards individual fish, it could be fish excluded from the group, loss of appetite etc. 6 fish is often cited as the number of fish where 6 fish start to act more normally, but the more the better.
Thats not to say you need to go out and buy more fish. You haven't said what size BiOrb you have and it may not be suitable for a bigger group of cherry barbs.
Thats not to say you need to go out and buy more fish. You haven't said what size BiOrb you have and it may not be suitable for a bigger group of cherry barbs.
I also want to raise some points that may not be related to your issues, but they are things you should be aware of.
BiOrb tanks don't have a good reputation in the hobby for a few reasons.
The filtration on them is not very good. For biological filtration it relies almost 100% on the substrate that comes with the tank. This substrate produces a lot of voids that will trap a lot of detritus. You have to be very careful cleaning the substrate because too much cleaning will adversely affect your cycle. However not enough cleaning will allow all that detritus to build up and cause other issues. Its a fine line.
In fact a popular youtuber who specialises in filtration recently put out a video going through how he raised this issue with BiOrb and how they could easily fix their filtration. They weren't interested as it would reduce their "after sales". They are happy making aquariums with built in issues because they can then sell consumables which fix their problems. This is common across the aquarium industry. A lot of it is geared to selling products that you don't really need, that don't do any good, fixing problems that shouldn't (or dont) exist.
Another issue with the bowl type BiOrbs are they give very little "floor space" which limits available space for fish to establish territory. This can add to the stress levels in a tank.
Onto tank maintenance.
A water change every 6 weeks isn't really enough even in a tank with an efficient filtration system. At the very least change 1/3 of the water every 2 weeks. Every week preferably. Your nitrate is high and this is a symptom of both an insufficient water change regime and decaying waste left trapped in the substrate.
The filter you change every 6 weeks is a carbon filter. To have any effect this does need changing as carbon expires after 2 to 4 weeks. However carbon has very limited uses. It absorbs organic compounds. This is usually medication once the course has been completed, tannins from driftwood that colour the water, and phenols that give off odours. Medication is only a temporary situation. Tannins will eventually leech out. If you are keeping up with your water maintenance water shouldn't smell. Most of the time carbon isn't doing anything useful and its expensive. This is one of the "aftersales" I mention above. By all means, if its an expense you are comfortable with it won't do any harm to keep replacing the carbon filter, but as said most of the time it won't be doing anything useful.
Your test kit doesn't measure ammonia and strips are unreliable. It could be you have a water quality issue you aren't aware of. I would look at getting a liquid test kit. API FW master test kit is a good one to go for. It covers what you need (pH, ammonia, nitrite and nitrate), is more reliable than strips, is fairly easy to use, and as you get 100s of tests from a kit is much more cost effective long run than strips.
And your test strips doesn't have 2 measures of nitrate. They measure nitrate and nitrite. They are different.
NO2- is nitrite. That should be zero. You have it at 50.
NO3- is nitrate. That should be a positive value. You have it at zero.
Can you check these are the correct way around. Nitrite at 50 will be killing your fish pretty much instantly.
BiOrb tanks don't have a good reputation in the hobby for a few reasons.
The filtration on them is not very good. For biological filtration it relies almost 100% on the substrate that comes with the tank. This substrate produces a lot of voids that will trap a lot of detritus. You have to be very careful cleaning the substrate because too much cleaning will adversely affect your cycle. However not enough cleaning will allow all that detritus to build up and cause other issues. Its a fine line.
In fact a popular youtuber who specialises in filtration recently put out a video going through how he raised this issue with BiOrb and how they could easily fix their filtration. They weren't interested as it would reduce their "after sales". They are happy making aquariums with built in issues because they can then sell consumables which fix their problems. This is common across the aquarium industry. A lot of it is geared to selling products that you don't really need, that don't do any good, fixing problems that shouldn't (or dont) exist.
Another issue with the bowl type BiOrbs are they give very little "floor space" which limits available space for fish to establish territory. This can add to the stress levels in a tank.
Onto tank maintenance.
A water change every 6 weeks isn't really enough even in a tank with an efficient filtration system. At the very least change 1/3 of the water every 2 weeks. Every week preferably. Your nitrate is high and this is a symptom of both an insufficient water change regime and decaying waste left trapped in the substrate.
The filter you change every 6 weeks is a carbon filter. To have any effect this does need changing as carbon expires after 2 to 4 weeks. However carbon has very limited uses. It absorbs organic compounds. This is usually medication once the course has been completed, tannins from driftwood that colour the water, and phenols that give off odours. Medication is only a temporary situation. Tannins will eventually leech out. If you are keeping up with your water maintenance water shouldn't smell. Most of the time carbon isn't doing anything useful and its expensive. This is one of the "aftersales" I mention above. By all means, if its an expense you are comfortable with it won't do any harm to keep replacing the carbon filter, but as said most of the time it won't be doing anything useful.
Your test kit doesn't measure ammonia and strips are unreliable. It could be you have a water quality issue you aren't aware of. I would look at getting a liquid test kit. API FW master test kit is a good one to go for. It covers what you need (pH, ammonia, nitrite and nitrate), is more reliable than strips, is fairly easy to use, and as you get 100s of tests from a kit is much more cost effective long run than strips.
And your test strips doesn't have 2 measures of nitrate. They measure nitrate and nitrite. They are different.
NO2- is nitrite. That should be zero. You have it at 50.
NO3- is nitrate. That should be a positive value. You have it at zero.
Can you check these are the correct way around. Nitrite at 50 will be killing your fish pretty much instantly.
Last edited:
I agree with not adding more fish. But a 15 litre tank isn't suitable for cherry barbs. 100 litres is considered the minimum size tank for cherry barbs. Im sure you could work with smaller than 100 litres, but 15 litres will simply lead to poor quality of life for these fish.
In terms of getting a new tank set up - I usually allow a week for set up - is there any advice you can give for the intervening period and do you think the sick fish will survive a move? Should I do a water change straight away ?
How long to set up a new tank before adding fish really depends on how you plan on cycling the tank.
It typically takes 6 to 8 weeks to cycle a tank. You "might" get this down to 2 to 3 weeks if you have cycled filter material you can swap from an established tank into a new filtration system (you do).
If you plan on cycling the tank before moving your fish this is called a "fishless cycle" and involves replicating fish waste by dosing ammonia into the new tank so the bacteria has a food source and can grow sufficiently to support your fish before moving them.
If you plan on moving the fish and then cycling the tank with the fish in there, this is called a "fish in cycle" and involves lots of water changes to manage toxic water conditions until your cycle establishes.
Are you aware of the nitrogen cycle and how to cycle a tank? There is a different process for fishless and fish in cycling.
If you have been setting up tanks for a week before stocking them in the past, whether intentionally or not you have been doing a fish in cycle. And that week won't really have done anything useful beyond making sure the tank doesn't leak and all the equipment is working ok. If you are going down a fish in cycle route, set everything up, let it run 24 hours to ensure everything works ok and there are no leaks etc and add a small number of fish.
I really don't think your fish is sick. Its just acting a little abnormally, probably due to its circumstances. If in doubt, test the water (or get a sample to test later), and change some water. Your nitrate is on the high side, but not dangerously high. A water change will bring it down to a better level.
It typically takes 6 to 8 weeks to cycle a tank. You "might" get this down to 2 to 3 weeks if you have cycled filter material you can swap from an established tank into a new filtration system (you do).
If you plan on cycling the tank before moving your fish this is called a "fishless cycle" and involves replicating fish waste by dosing ammonia into the new tank so the bacteria has a food source and can grow sufficiently to support your fish before moving them.
If you plan on moving the fish and then cycling the tank with the fish in there, this is called a "fish in cycle" and involves lots of water changes to manage toxic water conditions until your cycle establishes.
Are you aware of the nitrogen cycle and how to cycle a tank? There is a different process for fishless and fish in cycling.
If you have been setting up tanks for a week before stocking them in the past, whether intentionally or not you have been doing a fish in cycle. And that week won't really have done anything useful beyond making sure the tank doesn't leak and all the equipment is working ok. If you are going down a fish in cycle route, set everything up, let it run 24 hours to ensure everything works ok and there are no leaks etc and add a small number of fish.
I really don't think your fish is sick. Its just acting a little abnormally, probably due to its circumstances. If in doubt, test the water (or get a sample to test later), and change some water. Your nitrate is on the high side, but not dangerously high. A water change will bring it down to a better level.
Colin_T
Aquarium Advice Addict
Are all the cherry barbs red?
If yes they are all male and the one hiding in the plants is being bullied. A bigger tank (which you plan on doing) and a few females could change things, but at this stage, it appears to be taking cover in the plants to avoid conflict.
---------------------
300 mg/l (milligrams per liter) is the same as 300 ppm (parts per million). You have pretty hard water
Unless you are really attached to the cherry barbs, you might be better off keeping livebearers (mollies, swordtails, guppies and platies) or African Rift Lake cichlids. However, these will need a bigger. You can get a reverse osmosis (r/o) unit and connect it to a tap. The tap water will get forced through various filter media and that will remove most of the minerals from the water. The purified water is collected in a bucket and used at a 50/50 ratio with tap water to drop the GH to about 150ppm.
The drawback to r/o units is they tend to waste a lot of water. The good units have a 1:1 ratio of waste water to purified water. The waste water gets poured on the garden because it has all the minerals and stuff from the tap water. The lower grade r/o units can have a 2:1, 3:1 or 4:1 ratio and you get 2, 3 or 4 times the amount of waste water for 1 lot of purified water. If water is cheap then this isn't a big issue, but if you live in a dry climate or where water is expensive, then a r/o unit might not be the best option.
---------------------
SOLAR STILL
If you live in a warm climate, you can make a solar still and get pure water that way.
Get a large plastic storage container and put it outside in the sun.
Pour a bucket of water into the storage container.
Put a clean bucket in the middle of the storage container. Have a rock in the bucket to stop it floating around.
Put the lid on the storage container.
Put a rock or small weight on the lid in the middle, so the lid sags above the bucket.
As the sun heats up the container, water will evaporate and condense on the underside of the lid. The water will run towards the centre and drip into the bucket. When the bucket is full of water, you put it into a holding container and put the bucket back in the storage container with another bucket of tap water.
You get pure water with a pH of 7.0, 0 GH, 0KH and no wasted water, no power used and it's cheap to set up. You can then use this distilled water to mix with tap water to lower the GH and bring it into an range that is better for the cherry barbs.
If yes they are all male and the one hiding in the plants is being bullied. A bigger tank (which you plan on doing) and a few females could change things, but at this stage, it appears to be taking cover in the plants to avoid conflict.
---------------------
300 mg/l (milligrams per liter) is the same as 300 ppm (parts per million). You have pretty hard water
Unless you are really attached to the cherry barbs, you might be better off keeping livebearers (mollies, swordtails, guppies and platies) or African Rift Lake cichlids. However, these will need a bigger. You can get a reverse osmosis (r/o) unit and connect it to a tap. The tap water will get forced through various filter media and that will remove most of the minerals from the water. The purified water is collected in a bucket and used at a 50/50 ratio with tap water to drop the GH to about 150ppm.
The drawback to r/o units is they tend to waste a lot of water. The good units have a 1:1 ratio of waste water to purified water. The waste water gets poured on the garden because it has all the minerals and stuff from the tap water. The lower grade r/o units can have a 2:1, 3:1 or 4:1 ratio and you get 2, 3 or 4 times the amount of waste water for 1 lot of purified water. If water is cheap then this isn't a big issue, but if you live in a dry climate or where water is expensive, then a r/o unit might not be the best option.
---------------------
SOLAR STILL
If you live in a warm climate, you can make a solar still and get pure water that way.
Get a large plastic storage container and put it outside in the sun.
Pour a bucket of water into the storage container.
Put a clean bucket in the middle of the storage container. Have a rock in the bucket to stop it floating around.
Put the lid on the storage container.
Put a rock or small weight on the lid in the middle, so the lid sags above the bucket.
As the sun heats up the container, water will evaporate and condense on the underside of the lid. The water will run towards the centre and drip into the bucket. When the bucket is full of water, you put it into a holding container and put the bucket back in the storage container with another bucket of tap water.
You get pure water with a pH of 7.0, 0 GH, 0KH and no wasted water, no power used and it's cheap to set up. You can then use this distilled water to mix with tap water to lower the GH and bring it into an range that is better for the cherry barbs.
Thanks so much Colin - I really appreciate all the good advice and what an amazing forum. Yes they are all red which seems to support the bullying theory - what I have learned is that I need to get a much bigger tank asap and perhaps as you say introduce some females in a little while.
Our water here is very hard so your suggestion of an r/o unit sounds a good one. We live in the uk so some sunshine but not all year round!
I’ll start looking for. New tank now because I don’t want the fish to be any more stressed than they are - I feel very responsible that I took advice from the shop rather than reading up fully first
Many thanks
Adana
Our water here is very hard so your suggestion of an r/o unit sounds a good one. We live in the uk so some sunshine but not all year round!
I’ll start looking for. New tank now because I don’t want the fish to be any more stressed than they are - I feel very responsible that I took advice from the shop rather than reading up fully first
Many thanks
Adana
Cherry barb update
Hi guys - I thought I would give you an update - I now have a 125 litre tank - it’s been cycled, completely I used Fritzyme 7 to introduce good bacteria - I also used an existing sponge from the old filter- a few real plants for oxygenation - I’ve tested the water and everything is where it should be- I have just introduced the fish and they are swimming about at some speed bumping into the glass- the light has been kept off until they settle - some shady places to hide- given that they have gone from such a small tank 15l to such a large one, would you consider this normal behaviour and is there anything I should be watching for?
Thankyou!
Hi guys - I thought I would give you an update - I now have a 125 litre tank - it’s been cycled, completely I used Fritzyme 7 to introduce good bacteria - I also used an existing sponge from the old filter- a few real plants for oxygenation - I’ve tested the water and everything is where it should be- I have just introduced the fish and they are swimming about at some speed bumping into the glass- the light has been kept off until they settle - some shady places to hide- given that they have gone from such a small tank 15l to such a large one, would you consider this normal behaviour and is there anything I should be watching for?
Thankyou!
Colin_T
Aquarium Advice Addict
Picture of the new tank so we can see how it's set up for the fish?
A lot of fish will check out the new tank, especially if it's bigger. Things to watch out for include rapid breathing, gasping at the surface or near a filter outlet, white marks on their mouth or nose. The white marks are usually bruises from bumping into things.
Monitor ammonia, nitrite and nitrate levels for a month or so and enjoy watch the fish in their new home.
-----------------
AQUARIUM LIGHTS
TURNING LIGHTS ON AND OFF
Stress from tank lights coming on when the room is dark can be an issue. Fish don't have eyelids and don't tolerate going from complete dark to bright light (or vice versa) instantly.
In the morning open the curtains or turn the room light on at least 30 minutes (or more) before turning the tank light on. This will reduce the stress on the fish and they won't go from a dark tank to a bright tank instantly.
At night turn the room light on and then turn the tank light off. Wait at least 30 minutes (or more) before turning the room light out. This allows the fish to settle down for the night instead of going from a brightly lit tank to complete darkness instantly.
Try to have the lights on at the same time each day. Use a timer if possible.
--------------------
TWO LIGHT UNITS
If you have two light units on the tank, put them on timers and have one come on first, then an hour later the second one can come on. It will be less stressful for the fish.
In the evening, turn the first light off and wait an hour, then have the second light go out.
If the lights have a low, medium and high intensity setting, have them on low in the morning, then increase it to medium after a couple of hours, and then high for the main part of the day. In the evening, reverse this and have the medium setting for a few hours, then low. Then turn the lights off.
--------------------
LIGHTING TIMES
Most aquarium plants like a bit of light and if you only have the light on for a couple of hours a day, they struggle. If the light doesn't have a high enough wattage they also struggle. Try having the tank lights on for 10-12 hours a day.
If you get lots of green algae then reduce the light by an hour a day and monitor the algae over the next 2 weeks.
If you don't get any green algae on the glass then increase the lighting period by an hour and monitor it.
If you get a small amount of algae then the lighting time is about right.
Some plants will close their leaves up when they have had sufficient light. Ambulia, Hygrophilas and a few others close their top set of leaves first, then the next set and so on down the stem. When you see this happening, wait an hour after the leaves have closed up against the stem and then turn lights off. It's worth investing in a couple of these plants just to see how they do. They are generally good in most aquariums and give you a rough idea of if you have enough light on the tank.
Plant lights should have equal amount of red and blue light and a bit less green light.
A lot of fish will check out the new tank, especially if it's bigger. Things to watch out for include rapid breathing, gasping at the surface or near a filter outlet, white marks on their mouth or nose. The white marks are usually bruises from bumping into things.
Monitor ammonia, nitrite and nitrate levels for a month or so and enjoy watch the fish in their new home.
-----------------
AQUARIUM LIGHTS
TURNING LIGHTS ON AND OFF
Stress from tank lights coming on when the room is dark can be an issue. Fish don't have eyelids and don't tolerate going from complete dark to bright light (or vice versa) instantly.
In the morning open the curtains or turn the room light on at least 30 minutes (or more) before turning the tank light on. This will reduce the stress on the fish and they won't go from a dark tank to a bright tank instantly.
At night turn the room light on and then turn the tank light off. Wait at least 30 minutes (or more) before turning the room light out. This allows the fish to settle down for the night instead of going from a brightly lit tank to complete darkness instantly.
Try to have the lights on at the same time each day. Use a timer if possible.
--------------------
TWO LIGHT UNITS
If you have two light units on the tank, put them on timers and have one come on first, then an hour later the second one can come on. It will be less stressful for the fish.
In the evening, turn the first light off and wait an hour, then have the second light go out.
If the lights have a low, medium and high intensity setting, have them on low in the morning, then increase it to medium after a couple of hours, and then high for the main part of the day. In the evening, reverse this and have the medium setting for a few hours, then low. Then turn the lights off.
--------------------
LIGHTING TIMES
Most aquarium plants like a bit of light and if you only have the light on for a couple of hours a day, they struggle. If the light doesn't have a high enough wattage they also struggle. Try having the tank lights on for 10-12 hours a day.
If you get lots of green algae then reduce the light by an hour a day and monitor the algae over the next 2 weeks.
If you don't get any green algae on the glass then increase the lighting period by an hour and monitor it.
If you get a small amount of algae then the lighting time is about right.
Some plants will close their leaves up when they have had sufficient light. Ambulia, Hygrophilas and a few others close their top set of leaves first, then the next set and so on down the stem. When you see this happening, wait an hour after the leaves have closed up against the stem and then turn lights off. It's worth investing in a couple of these plants just to see how they do. They are generally good in most aquariums and give you a rough idea of if you have enough light on the tank.
Plant lights should have equal amount of red and blue light and a bit less green light.
Colin_T
Aquarium Advice Addict
If the water is good, you can add females any time. Try to have at least 4 females. They are brown in colour, have a fatter white belly and should not have red on them.
Make sure you can see inside and right around the ornaments and plants. If a fish dies under something or in a cave, it can cause water quality problems before you see it.
---------------
You should try to have a similar lighting cycle to nature. Have yellow light first, then add red, then green, blue and white. In the afternoon, reverse that pattern.
You can also start off with 10% light and increase the intensity over a couple of hours. And in the evening reverse it so you slowly reduce the intensity over a few hours.
Make sure you can see inside and right around the ornaments and plants. If a fish dies under something or in a cave, it can cause water quality problems before you see it.
---------------
You should try to have a similar lighting cycle to nature. Have yellow light first, then add red, then green, blue and white. In the afternoon, reverse that pattern.
You can also start off with 10% light and increase the intensity over a couple of hours. And in the evening reverse it so you slowly reduce the intensity over a few hours.
