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Stunted growth and algae in low tech setup

I feel your pain and your photo of the tank when healthy is lovely, and understand how disheartening deterioration in a tank can be, but it happens to most of us on occasions. This summer I put an air stone in my tank before going on holiday - fear of heat and low oxygen. I lost some fragile plants because of this. I have been checking the water the last few days and reckon an air stone took my dissolved CO2 from >20ppm to <2 despite injection of CO2 even with the lights on. You therefore, I suspect, might be right that you have crashed CO2 levels with more vigorous surface agitation.

I'm a great fan of choosing first whether to go low light or high light and selecting plants accordingly, I have found over the last nearly 4 decades of using CO2 that high light, fragile and red plants do need injected CO2 and that medium plants, to really thrive, need more light than is sometimes suggested on the labels. LED is not miraculous and I find I need to use about the same wattage with most mid-range LED lights as I would have used with fluorescent tubes. And hard water and no injected CO2 certainly means plants are light hungry to successfully photosynthesise.

I think you should work out what your CO2 levels are, and light levels, and maybe upgrade lighting, it may have faded over time, your tank does look to me a bit dull in your earlier photographs and think about adjusting filtration and adding CO2, though with the right plants as your photo shows a tank can work without CO2 injection, but it is harder to maintain long-term. I doubt there is any magic in commercial bottle to restore your tank to its former glory so be suspicious of the bottles aquarium shops are so keen to sell us, but light and some CO2 works wonders, it is the basis of plant growth, and I have used yeast & sugar, with great success to just "tilt the balance". Once plants start growing faster they generally out-compete most algae species.

I try to keep an open mind, and I don't fully understand all the science and I have to adjust the management of my tank to address seasonal issues - sunlight in the spring and more recently high temperatures. I also, do play about I admit with my water chemistry, my tap water is very hard, I aim for moderately soft water, very hard water is fine for some plants but not all the plants I like to grow. I also personally don't add Phosphate to my water column at all and only add fertiliser to my substrate - normally osmocote, and in modest amounts.

Good luck and don't feel you need to spend a fortune to revive your tank to its former glory but do try and work out what factors have moved against the plants. A photograph of my tank currently, I have essentially lost my Rotala macrandra - low CO2 and high temperatures I think.
 

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You mentioned you have a gh test? Although they aren't lab accurate I would use it on your tap water to get a rough idea of what you are working with. Otherwise you could try asking your local fish shop what the local water is like or they may test a sample for you.
I just tested the GH of my tap water and, according to the drop test, it is 21 dGH. I'm not very good at maths but if I calculate correctly, adding 1 liter of tap water to 9 liters of RO water should yield about 2dGH ?

I have been checking the water the last few days and reckon an air stone took my dissolved CO2 from >20ppm to <2 despite injection of CO2 even with the lights on. You therefore, I suspect, might be right that you have crashed CO2 levels with more vigorous surface agitation.
I didn't think it might be an issue in a non CO2 injected tank but now that I think about it, I had almost zero surface agitation with the previous filter. I just repositioned my spray bar to create less surface agitation and will see if it changes anything in the next weeks.
and I have used yeast & sugar, with great success to just "tilt the balance"
I might also try that. I was afraid of trying it after reading horror stories about bottles exploding and walls covered in yeast and sugar, that's what kept me from trying this. Do you happen to have a link describing how you do it ? Or would you mind briefly describing your method ?
A photograph of my tank currently, I have essentially lost my Rotala macrandra - low CO2 and high temperatures I think.
It is absolutely gorgeous, your fishes must be so happy in there !
 
I just tested the GH of my tap water and, according to the drop test, it is 21 dGH. I'm not very good at maths but if I calculate correctly, adding 1 liter of tap water to 9 liters of RO water should yield about 2dGH ?

Yep, absolutely right. Having had a quick read up, I would probably go for 3 litres of tap to 7 litres of RO to give you around 6dGH. That's still on the soft end for your fish, which don't sound like they need the extremes so also not so soft that you have to worry about issues related to having extremely soft water.
 
Quick update 10 days after my last post :
Things are looking better. It's of course too early to celebrate and I don't want to be too optimistic but the hygrophila polysperma is growing and, besides some algae that was already there on the lower leaves, the new ones don't seem to be affected.
I will continue to monitor this and will keep this post updated for a while.

Assuming things are indeed better, what would be the more plausible cause of the problems I had in your opinion ? GH too low ? Too much organic waste ? CO2 too low because of surface agitation ? I'm really trying to determine what my error was in order to not do it again.
 
Hi all,
Quick update 10 days after my last post :
Things are looking better. It's of course too early to celebrate and I don't want to be too optimistic but the hygrophila polysperma is growing and, besides some algae that was already there on the lower leaves, the new ones don't seem to be affected.
Good.
Assuming things are indeed better, what would be the more plausible cause of the problems I had in your opinion ?
What have you changed?

cheers Darrel
 
Hi Darell,

I did a 50% water change with 90% RO and 10% tap water (tap water tested to 21°GH). It gave a 110µs tds reading wich is double of what I normally use for my water changes.
I also did a deep clean of the tank, vacuuming a lot of the detritus, cleaning the filter and heater with hydrogen peroxide.
Finally, I reoriented my spray bar to ensure minimal surface mouvement.
 
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