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Discussion Starter · #1 · (Edited)
Hi so i’ve got this 20 gallon long, dirted tank that has been running for almost a year. A quick aside, before this i was running it with a lot of crypts and a few stems in back, no heater and had a huge issue with cyano from too long/too bright led. I redid the entire tank with new substrate and plants hoping to rid the cyano. It wasn’t until recently that the plant growth halted.

this tank was entirely rotala (heavily planted) and there were pockets of cyano but not bad. I then removed almost all the rotala, added houseplants on top to help shade the tank, added some young crypts and salvinia. Things were okay but the salvinia was coated in cyano and a little on the substrate. I removed the floaters and cut the light intensity but not duration. Lately i havent had cyano on the tank walls but heavily on the substrate in front where it gets the most light and thicker/fasting spreading than before. Today i vacced it out as usual and added a new filter with better flow. The wisteria in back is not growing at all and it was doing pretty well when the tank was full of rotala. The crypts are doing ok.

what’s the deal? am i looking at potentially 0 nitrate/phosphate? I did add macro nutrient mix a few weeks back but hard to tell if it helped. Also i only have no3 so not really a good source of nitrates.

also i think part of the issue is stocking. This tank houses two pea puffers and (maybe) 2 shrimp. This means no flake only live foods like snails/daphnia. Also no snails to do snail things. Any idea how i can fix this tank? Temp = 25

now
Plant Rectangle Vegetation Shade Grass

before
Plant Terrestrial plant Vegetation Grass Shrub
 

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I did a very quick search for "cyano" on this website and the interesting thing is going back as far as the early 2000s the photos look just like yours: tanks with a lot of water but very few plants. The best defense against algae and cyano is a heavily planted tank.

What is your lighting schedule like? My understanding is that BGA/cyano as well as algae in general compete for the same nutrients as plants. They also use photosynthesis in similar ways. Plants require a lot more CO2 in order to grow and by midday they've exhausted most of it. So, unless your lighting includes a midday "siesta" period where they are simply turned off for a period of time, all of that extra light is benefitting the cyano and not your plants.
 

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Discussion Starter · #3 ·
I did a very quick search for "cyano" on this website and the interesting thing is going back as far as the early 2000s the photos look just like yours: tanks with a lot of water but very few plants. The best defense against algae and cyano is a heavily planted tank.

What is your lighting schedule like? My understanding is that BGA/cyano as well as algae in general compete for the same nutrients as plants. They also use photosynthesis in similar ways. Plants require a lot more CO2 in order to grow and by midday they've exhausted most of it. So, unless your lighting includes a midday "siesta" period where they are simply turned off for a period of time, all of that extra light is benefitting the cyano and not your plants.
no siesta and 12-14 hours. Things were growing before and there was significant cyano but they seem to have just halted now.
 

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Discussion Starter · #7 ·
It looks like your tank ran out of steam. The dirt is depleted.
I don't see too many fish so I assume you don't feed them too much so the dirt isn't replenished with organic matter.

You can start over.
Yeah its just the two puffers so no fish food. Ive been thinking about restarting for awhile so i guess ill have to go that route. Just a little nervous to move my fish. I think im going to do potted plants this time so its easier to maintain.
 

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Not sure why do you want to restart the whole tank just to face the same issue again eventually. :) When dirt in my tanks depleted, I just started adding root tabs/sticks (many different options out there, including very cheap or even DIY with Osmocote) and/or adding liquid ferts. I take it as a part of feeding routine now - I provide fish food, shrimp food and plant food. Finding the right balance between light intensity, duration and ferts amount is interesting experience, but I basically ended up with "Estimative Index daily/PPS" values. I would consider "EI low light/weekly" doses for your tank in its current status and see how it goes. I use floating plants as bio indicator of deficiencies as they react quickly to changes and are not limited by CO2 in the water.

Very handy calculator should you decide to go with liquid ferts (DIY or commercial products):
 

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It just seems like your tank is low activity thus you have slow growing plants. It’s a pretty big tank with few fish and plants. Maybe think about how much “biomass” you’re adding with fish food. Biomass in means biomass out. Diana always talks about feeding her fish “plus extra for the plants”. If there’s no food coming in, there would be no plant growth coming out. I don’t think the soil is depleted, that should take years and years (like a decade or more). I think your nitrogen cycle is nonexistent. Think “Fish food -> Fish (animal) poop -> Bacteria eating fish waste -> Plants absorbing waste -> Plant growth -> Humans trimming plant overgrowth”.
The fish food IS the nitrogen fertilizer for your plants. The Walstad “low maintainence” tank should look like feeding fish, trimming plant overgrowth and the occasional partial water change. That’s it. I think you need some bio-activity! Stop vacuuming, get some snails and shrimp to help clean instead and maybe even rethink your filter. You’re taking the plant food out of the tank when you do that.
 

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You may already know this but cyano is a bacteria, not algae. Nothing will eat it so a "clean up crew" won't help. I had a case of it a long time ago when I first got my 29 gallon tank. I tried a blackout, excessive vacuuming, lowering light levels, etc. The only way I got rid of it was dosing erythromycin.
 

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You may already know this but cyano is a bacteria, not algae. Nothing will eat it so a "clean up crew" won't help. I had a case of it a long time ago when I first got my 29 gallon tank. I tried a blackout, excessive vacuuming, lowering light levels, etc. The only way I got rid of it was dosing erythromycin.
Everything competes. Every tank is going to have some cyanobacteria. His tank is a bacteria soup because there isn’t enough other biomass to compete for light and nutrients. Cyanobacteria is not immortal, it’s just has little competition in this case. He has only two fish. His biodiversity of his plants is also very low for a 20 gallon tank. He needs something big and fat like a tiger lotus to take up space. A ”siesta“ period would also help. I think he needs to add more plants, (floating like coontail too) and fish instead of tearing the whole tank down.
I also think we’re getting half the picture. From what little I can see, the “house plants” on the top seem to be growing fine. He needs more plants and different plants growing in the water. Low tech tanks seem to favor low tech solutions.

Here’s a picture of one of Diana’s tanks. Very different looking than YodelMogul’s! I think he just needs more of everything!
Plant Plant community Botany Terrestrial plant Organism
 

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Your tank seemed to be doing fine before with the Rotala. Then you removed the Rotala and added houseplants. These are big changes that upset a once stable ecosystem.
Could be that the houseplants are dominating the submerged plants in some way and getting the majority of the nutrients. The BGA was able to move in.
I would consider fertilizing the substrate, manually removing the BGA, treating tank with erythromycin, and then adding more plants.
You have a challenge here...
Good luck.
 

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Discussion Starter · #14 ·
the houseplants seem to be doing pretty well. i could easily fill this up with plants but they seem to just be melting without fish food. Today i vacced out some of the cyano, added root Tabs for npk and tomorrow im going to try the ultra life slimer remover since i have that on hand. i have a sort of vision but if this all fails i may remove the dirt and just add a couple pots in.
 

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Discussion Starter · #15 ·
Everything competes. Every tank is going to have some cyanobacteria. His tank is a bacteria soup because there isn’t enough other biomass to compete for light and nutrients. Cyanobacteria is not immortal, it’s just has little competition in this case. He has only two fish. His biodiversity of his plants is also very low for a 20 gallon tank. He needs something big and fat like a tiger lotus to take up space. A ”siesta“ period would also help. I think he needs to add more plants, (floating like coontail too) and fish instead of tearing the whole tank down.
I also think we’re getting half the picture. From what little I can see, the “house plants” on the top seem to be growing fine. He needs more plants and different plants growing in the water. Low tech tanks seem to favor low tech solutions.

Here’s a picture of one of Diana’s tanks. Very different looking than YodelMogul’s! I think he just needs more of everything!
View attachment 75407
^^^^^ I agree completely...definitely needs more plants. LOTS more plants. :)
The plants im adding are melting like ive never seen before. I think it has to do with no fishfood and only 2 fish. Im not sure how to dose enough nitrate with just kno3 either. Im trying root tabs currently so well see.
 

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The plants im adding are melting like ive never seen before.
New plants will do that. It's just the way they have been produced on a mass scale. By the time we purchase them in a store they have spent most of their existence as emersed plants grown under humid conditions. The melting period is their way of adapting to submersed conditions. It's frustrating, but don't panic.
 

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The plants im adding are melting like ive never seen before. I think it has to do with no fishfood and only 2 fish. Im not sure how to dose enough nitrate with just kno3 either. Im trying root tabs currently so well see.
Agreed. Yes, BUT, if you have no where for the newly introduced nitrogen from feeding new fish to go your algae problem will get worse. Try plants that won’t melt like a betta bulb and a tiger lotus bulb (cheap too). Coontail can also help you catch up as your other plants recover.
 

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Discussion Starter · #18 ·
New plants will do that. It's just the way they have been produced on a mass scale. By the time we purchase them in a store they have spent most of their existence as emersed plants grown under humid conditions. The melting period is their way of adapting to submersed conditions. It's frustrating, but don't panic.
Theyre from my other tanks and grown completely submerged. the vals i added a few weeks ago havent melted but they havent grown much either. most of the rotala and wisteria i had is either stunted or melted away. It must be nutrients.
 

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Theyre from my other tanks and grown completely submerged. the vals i added a few weeks ago havent melted but they havent grown much either. most of the rotala and wisteria i had is either stunted or melted away. It must be nutrients.
Careful on the nutrients. A nitrogen bomb in your tank could lead to bacteria and algae growth. Give the plants time to chill.
 

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"They are from my other tanks and grown completely submerged. The vals I added a few weeks ago haven't melted but they haven't grown much either. Most of the rotala and wisteria I had is either stunted or melted away. It must be nutrients."

So it is not an adjustment of emergent plants to submerged form. Something's off in this tank and it also could be toxins in either water or substrate. I find it hard to believe that this tank, which has a soil underlayer and dead plants would be nutrient-deprived.

If earlier you had a lot of root death in substrate, it could be toxicity from dead and decomposing roots. If you have soft water and there is not enough Ca, it may be toxicity from heavy metals in the water.

Try putting some healthy stem plants at the water surface just under the lights in the problem tank and in a normal tank. If the plants start melting in the problem tank, then you can surmise that the water is causing the problem.
 
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