Low light tank problems - BBA & leaf drop

[vthokie]

I have a 75 low-light tank with crypts (spiralis & wendtii), anubias, java moss, java fern, java lace, water sprite and hornwort. I had some deficiency problems (previous post) which have been improving since I began dosing. Most plants are doing well.

I have 2 issues at the moment:

1) Every day I find a couple of leaves from the crypt spiralis that have detached from the base. At first I thought it was just older leaves that were covered in algae from when I set up the tank, but now I've noticed that newer leaves are detaching as well. The Seachem Potassium bottle suggests that those are symptoms of potassium deficiency.

2) I have some BBA and some green spot algae. Nothing too bad...yet, but the BBA does seem to be spreading. I suspect this may be due to low nitrates & phosphates. I have not done a PWC for 4 weeks hoping to build up the nitrates, but they have remained the same.

I would consider the tank to be moderately planted.

I have most of the Seachem ferts except trace but I've been very conservative in my dosing so far since I have a fear that I'm going to make things worse!

The numbers:
light: 2-55W CF bulbs
substrate: fine gravel

pH: 7.4
Ammonia: 0
Nitrites: 0
Nitrates: 5ppm
Phosphates: 0.1ppm
GH: 6
KH: 3
Temp: 78F

Fish load: 19 small-med. tiger barbs, 1 blue gourami, 1 rainbow shark (all doing great)
I have also added sponges to the HOB outflow to reduce surface agitation to reduce loss of CO2.

Dosing:
Flourish Potassium: 12.5ml two times weekly
Flourish Comprehensive: 7.5ml two times weekly
Flourish Excel: 8.75 once per week
Flourish Iron: 7.5ml once per week
Flourish Nitrogen: 2ml (just one dose so far)
Flourish Phosphorous: 2ml (just one dose so far)
Flourish Fert tabs
No added CO2

Any suggestions on how to resolve these problems? Should I go heavy on the nitrogen/phosphorous dosing to control the BBA? Will increasing potassium prevent the leaves from falling?

Thanks for any help!

 

[zenkatydid]

as i understand, you cannot overdose potassium, so if you're concerned, up the dosage.

are you sure the crypts aren't just doing a melt and regrow cycle? how long have they been in the tank? have you moved them, or changed lighting or anything else recently? any sudden change can cause them to lose their leaves and regrow.

i definitely think you can dose phosphates - i've got 0.5ppm and have been told to dose it, so it looks like you're almost bottoming out there.

i also know that using excel at a higher dose can kill BBA, though i'm not sure of the details, so will wait for someone more knowledgable to come along.

 

[Lonewolfblue]

Another thing, Excel shouldn't be dosed once a week. It needs to be dosed daily, as it only lasts for a day. So it's really not doing you much good only dosing once a week.

 

[rich311k]

How much light do you have? I would dose the excel as recommended and try adding 10ppm N and 1 ppm phosphate once per week and see how it goes. With a low light tank minimum water changes could work well for you. That 5 ppm nitrate is worrisome low nitrates can lead to large algae problems.

 

[Plantbrain]

Do you use CO2?

Regards,
Tom Barr

 

[7Enigma]

Doesn't look like it. I agree the Excel dosing should either be cut out or used on a daily or every other day basis. I thought Seachem stated that the algae cannot use the carbon in Excel, but BBA generally comes about from fluctuating CO2 levels (wondering if Excel can also). Obviously once you bottom out a fert (such as nitrogen) all bets are off any any opportunistic algae present will grow.

With your size tank I would recommend upping the dosage of your ferts (especially the nitrogen, and also the phosphate), letting your current stock run out, and switch over to dry ferts. I think you might be very close to zero on both the nitrAte and the phosphate (GSA is generally considered a sign of low phosphates, and your 0.1ppm measurement is very low). Even with your low light setup, I think the ferts will pay for themselves in a year or so.

Have any pictures of the tank for our reference?

 

[vthokie]

I updated the info in my original post. I forgot to include lighting, substrate and fert tabs.
I have 2 55W CF bulbs, fine gravel, and I use Seachem fert tabs.


zenkatydid: I don't think the crypts are melting. The leaves are fine except that they break off at the base. I haven't moved them or made any changes.


I am not using CO2. I've thought about it, but I'm trying to keep the tank low-tech. That's one reason I went with gravel. In hindsight gravel was probably not a good move, but I have to live with my decision.

Anyway, thanks for the tip on the Excel. I thought the daily Excel dosing was just for high light tanks. I can see how it would get very expensive if I were to dose daily!

So, I will stop the Excel and 10ppm N & 1 ppm phosphate once a week. I have looked at dry ferts and will order them soon. I bought the Seachem stuff while I figured out what to do.

My wife & I are having a party this weekend, and she specifically mentioned my tank in the invitations! My immediate goal is to avoid an algae outbreak over the next few days!

I will post a pic of the tank tonight.

 

[Jchillin]

I'll just echo what has been mentioned in this thread as it mirrors my tank. Not so long ago, I dosed only potassium and completely ignored the fact that I had a very high plant mass. The result was BBA since I did not replace any of the depleted NO3 and the tanks previous ability to sustain enough CO2 was also gone.

Once I began the regimen mentioned above, the BBA disappeared, the plants that were salvageable look much better and I am one happy camper.

The method does work...just have to be a bit fanatical about it.

 

[Plantbrain]

If you go non CO2, you need to balance the fish load with the plant growth/biomass.
More plants is always better.

You do not do water changes, this will encourage BBA, unless you do the water changes daily or very frequent.

BBA do well when there's large CO2 changes.
Generally water changes add CO2.

This helps the algae and not so much the plants. Plantsd adapt to high or low CO2 given they have enough time to adapt, doing water changes weekly keeps the BBA going without much help to the plants.

If you use Excel, then you can go with Water changes and dosing more nutrients etc.

In most non CO2 tanks, water changes asre not done unless a large replanting is done, once every 3-9 months etc.

Just add water for top off.
This should solve the issue unless you simply have too many fish in the tank/not enougbh plant biomass.

After a week or two, you can start dosing if the fish load is light, but on the very lean side, no hobby test kits are going to give you useful info at such low ranges either.
Instead, watch the plants.

If they look a bit funny etc, add some N, P, K and traces.
Adding GH booster once a week is helpful also(see Greg Watson's site for more).

Regards,
Tom Barr

 

[7Enigma]

If you go non CO2, you need to balance the fish load with the plant growth/biomass.
More plants is always better.

You do not do water changes, this will encourage BBA, unless you do the water changes daily or very frequent.

BBA do well when there's large CO2 changes.
Generally water changes add CO2.

This helps the algae and not so much the plants. Plantsd adapt to high or low CO2 given they have enough time to adapt, doing water changes weekly keeps the BBA going without much help to the plants.

If you use Excel, then you can go with Water changes and dosing more nutrients etc.

In most non CO2 tanks, water changes asre not done unless a large replanting is done, once every 3-9 months etc.

Just add water for top off.
This should solve the issue unless you simply have too many fish in the tank/not enougbh plant biomass.

After a week or two, you can start dosing if the fish load is light, but on the very lean side, no hobby test kits are going to give you useful info at such low ranges either.
Instead, watch the plants.

If they look a bit funny etc, add some N, P, K and traces.
Adding GH booster once a week is helpful also(see Greg Watson's site for more).

Regards,
Tom Barr

Tom,

I would assume in smaller tanks where you can use buckets for PWC's (for instance I have a 20gallon and use a 5 gallon bucket for changes) that this isn't a problem? IE you can agitate the water prior to addition back into the tank so you don't have the CO2 fluctuation. I can definitely see how in larger tanks using a python could cause the CO2 fluctuation though....

 

[Plantbrain]

Perhaps.
If a lot of mulm gets pulled up, that's bad generally.

The goal, and underlying theme with a non CO2 tank, and one of the main reasons that it works is based on balancing between fish and plant biomass.

I went the other way and removed the fish entirely and dosed ferts alone to see.
Works very well, as the fish waste and the ferts I dosed are different and what I added was more balanced in terms of the plants.

So a hybrid of both works nicely(some fish and some topping off with ferts just once a week or two), see my site for more on non CO2 methods.

Some folks have set their water aside for 24-48 hours and then add it.
Not sure if it helps, I'd suspect it does.
Have not tried to induce BBA that way to see if that is correct or not.
That would be a key test and one I'll get to some time in the next 6-12 months.
Let me squeeze it in here in my free time
Ahh, but when the mood strikes, I'll get to it. I'm a bit critical about the methods used to show it as I've induced BBA effectively many times in FW CO2 planted tanks and gotten rid of it in every plant tank method type that's commonly used today.

Do not get me wrong, if you do a lot more water changes, say 2-3 or more a week, then you start adding stable levels of CO2 to the tank each day of the week. If you do not do anywater changes for months, then you also beat BBA and other algae.

So that middle disturbance ground appears to be the issue.

You need to leave things alone for no less than month if you go that way and do 3x a week good sized water changes. Both seem to get rid of BBA. Now you could try doing a series of 5% water changes, but you may as well not bother as it'll not effect the tank unless you do them daily etc....

So you get back to go all out or don't use any Gas/water changes.

They both work for the same reason, stable CO2 levels that the plants take a few weeks to adapt to and algae don't like in the presence of high plant biomass that's well adapted to stable CO2 concentrations.

Regards,
Tom Barr

 

[vthokie]

Here's a current pic of my tank. The java moss and water sprite on the left look better in reality than in the pic. The surface plants are water sprite and hornwort. You can see where I've scraped off some algae from the back wall.

The dark blotches on the gravel is the BBA.

Would you consider this to be lightly planted or moderately planted?

Thanks for all the great info so far!

 

[Jchillin]

I'd say lightly planted.