Plants dying, can't work out why

[Mike_]

Hi,

I am coming up to 2 months in a new 400l tank and the plants are growing well but dont seem to healthy.

Tank 400l
Filters 2x oase thermo 600
Temp 25c
Stocking level light
Co2 art inline injection at 4 dps
4 x Lominie astra f20s

The co2 comes on at 7am and goes off at 4pm
The lights come on at 8am and go off at 5pm

The tank has aqua soil and substrate below the sand

I dose 2 times a week double the recommended dose of tnc complete as per aquarium gardens advice due to plant level

40% water change every week

Ph 7.6
Ammonia 0.25 ppm
Nitrite 0 ppm
Nitrate 5 to 10 ppm

Any help or advice greatly appreciated as dont wish to lose the plants

Pics to help

[Caliban07]

Hi Mike,

How many millilitres do you dose and how many times do you dose them per week?

Edit: just saw that you dose twice but how many millilitres?

[Mike_]

Recommended is 1ml per 10l and I do 2ml

So roughly 80ml 2 x a week

[Caliban07]

Originally Posted by Mike_

Recommended is 1ml per 10l and I do 2ml

So roughly 80ml 2 x a week

If you are not familiar with the Estimative Index (EI) it is supposed to provide unlimited nutrition in a high light tank. The targets are:

Nitrogen (from potassium nitrate KNO3) = 7.5ppm

Phosphate (prom potassium phosphate KH2PO4) = 0.3ppm

Iron = 0.2ppm

You are supposed to dose these 3x per week then do a 50% water change on the 7th day.

Rotala butterfly nutrient calculator uses Iron (Fe) as a dosing guide for the Estimative Index when you select TNC complete.



As you can see you need to dose 100ml of TNC complete in a 400l tank to reach 0.2ppm Iron (Fe) but this only provides 3.75ppm of nitrogen. Nitrogen is what the plants need most so this is something to he aware of. It’s also mobile within the plant so should improve pale leaves, along with iron and magnesium.

With that said I don’t believe this is a nutrient issue given the substrate you are using and your current dosing. The translucency of the sword plants suggest a co2 issue. Try putting the co2 on another hour earlier. Then take it from there.

Also be sure to only focus on new growth for the time being. Old growth can be deceiving.

Lastly, make sure your flow rates and patterns are good enough to push the co2 infused water around to all of the plants.

*important*

When turning the co2 on earlier be sure to observe the live stock throughout and improve surface agitation.

Also note, new planted tanks go through a phase of disappointment almost inevitably. This is still a new tank. Perseverance is key. Once the biofilter stabilises, things will click in to place and things will start growing.

Regards
CJ

[Mike_]

Originally Posted by Caliban07

If you are not familiar with the Estimative Index (EI) it is supposed to provide unlimited nutrition in a high light tank. The targets are:

Nitrogen (from potassium nitrate KNO3) = 7.5ppm

Phosphate (prom potassium phosphate KH2PO4) = 0.3ppm

Iron = 0.2ppm

You are supposed to dose these 3x per week then do a 50% water change on the 7th day.

Rotala butterfly nutrient calculator uses Iron (Fe) as a dosing guide for the Estimative Index when you select TNC complete.

Attachment 322758

As you can see you need to dose 100ml of TNC complete in a 400l tank to reach 0.2ppm Iron (Fe) but this only provides 3.75ppm of nitrogen. Nitrogen is what the plants need most so this is something to he aware of. It’s also mobile within the plant so should improve pale leaves, along with iron and magnesium.

With that said I don’t believe this is a nutrient issue given the substrate you are using and your current dosing. The translucency of the sword plants suggest a co2 issue. Try putting the co2 on another hour earlier. Then take it from there.

Also be sure to only focus on new growth for the time being. Old growth can be deceiving.

Lastly, make sure your flow rates and patterns are good enough to push the co2 infused water around to all of the plants.

*important*

When turning the co2 on earlier be sure to observe the live stock throughout and improve surface agitation.

Also note, new planted tanks go through a phase of disappointment almost inevitably. This is still a new tank. Perseverance is key. Once the biofilter stabilises, things will click in to place and things will start growing.

Regards
CJ

Thanks for the advice

Just to clarify first off i will turn on the c02 an hour earlier and monitor fish behaviour

secondly am i right in understanding that you recommend upping the dose to 100ml 3 times a week for ideal nutrition.

i believe the flow shouldnt be an issue as it has 2 600l filters in opposite corners creating circular flow.

final thing is in the entire life of the tank i haven't had any signs of algae what so ever up until recently where a small area of sand in the foreground has started to go green with algae, what would your recommendation be about this

Thanks
Mike

[Caliban07]

Hi Mike

I suggest trying to up the co2 first and monitor fish before we look at nutrients. If algae is starting now nutrients may exacerbate it.

Most of the plants we use in aquariums are semi Aquatic and so in nature spend seasonal periods exposed to atmospheric co2. When they are held underwater they need to regulate enzymes to maximise their uptake and utilisation of co2. This make plants sensitive to changing degrees of co2 levels. They likely discard (melt) leaves off in favour of producing a new leaf which has a more suitable concentration of the enzyme based on the levels of co2 in the tank. If this fluctuates to much the plants will mostly discard leaves. This is why I recommend good surface agitation with co2. Even though it wastes more gas the co2 level will cap at a high and stable level.

Secondly, because photosynthetic mechanisms are disabled at night the plants are actually at a disadvantage at lights on because the photosynthetic mechanisms do not work immediately and the light damages their tissue structure. It takes about 1/2 hour or so for the systems to be enabled and functioning but you want co2 to be high when lights come on to limit the damage.

Because the intensity of light also dictates how much co2 is required, you can also try reducing the light intensity to maximise co2 usage.

Hmm, so many reasons why algae occurs. My biggest suspicion is that they are triggered in tanks that have varying degrees of decay (organic matter production) which could certainly be true if the plants are melting. The algae may have taken a longer while to show up due to the sheer volume of the tank. As they say, the solution to pollution is dilution. you can try changing water more often but also remember that your tank is still in the transition period between new and mature. Algae is inevitable in 90% of tanks (especially high tech) and you would likely have seen it earlier if the tank was smaller.

[Mike_]

Update

I have upped the c02 and it has been a few weeks now, the fish are fine and there is no change in behaviour, The water parameters are all still good.

yet the plants still don't seem to be doing well, pics below

what if anything can i try next

thanks
Mike

[Caliban07]

Try adding more nitrogen and magnesium. In the last picture I see chlorosis. The leaf will turn green again if it’s a nitrogen or magnesium deficiency. If it doesn’t try adding more iron. Iron is not a mobile nutrient and so it will show in greener newer leaves.

There does appear to be some decent looking leaves appearing though which is a good sign. Never ever focus on older leaves unless the newer leaves are turning brown or getting algae covered quickly.