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Persistent water clouding issue

625 Views 2 Replies 2 Participants Last post by  MMacG1167
I have a 20 gallon long tank at work that I have had a persistent (several months) clouding problem with. I do approximately 70% water changes on a (usually) weekly basis - when I pour the old water out into a porcelain white sink it has a slight green tinge to it. This initially clears the water up but the clouding returns within 3-5 days that the tank is lit. Lighting time is 8 hours a day (9-5) Monday thru Friday, with no light on the weekends. It receives no direct sunlight. The tanks dimensions are 30" x 12" x 12". Lighting is provided by a Finnex FugeRay Planted+ Aquarium LED Light plus Moonlights, and the tank is open-top. The substrate is Fluorite Black Sand, and I put in weekly dose of 2ml of Flourish. The temperature is in the mid to low 70s and filtration is provided by an appropriately sized Aquaclear overflow filter. Unfortunately I don't have much in the way of water parameters, other than that the GH of the water is about 10 and the pH is not to either extreme. There are 6 ember tetras, 5 neon tetras, 1 thereadfin rainbow fish, 2 ottos, and 15-20 cherry shrimp. All appear to be in good health and color and have been so for a long time. I have tried doing CO2 fertilization but have ultimately abandoned it. I was using the method involving paintball canisters and they would run out quite quickly so I stopped. The clouding occurred with and without the use of the CO2. The plants are rotala indica, small green wendt's cryptocoryne, Anubis nana, Staurogyne repens, and java moss, which are all doing well or thriving. Dwarf Hairgrass, Green Bacopa, Red Ludwigia, and Hemianthus calitrichoides are either struggling or only holding their own. I had Rotala macrandra, Glossotigma, and Althernantera reinicki but they all did poorly and died off. I know the first two do better with CO2 but when I was providing it they still declined. There is also Pennywort, which for did well for a while but then began slowly declining and only a small amount remains.

I'm assuming my problem is an imbalance of nutrients and too much light, although the Finnex is made for that size tank and I wouldn't think that 40 hours should be excessive. In any case since it is at work it would be difficult to cut back on its period of illumination. Below are pictures of it both before and after a water change (unfortunately I cannot get them to post with the correct orientation). Does anyone have any suggestions or advice? Thanks.


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Hi MMacG1167,

Welcome to TPT!

Green water is an indication of too much light, it doesn't necessarily mean an imbalance of nutrients although that could be an issue. I can tell you with that amount of light and only dosing 2ml of Seachem Flourish weekly that the likely reason you lost those plants is they starved for lack of available nutrients. The Fugeray Planted + puts out about [email protected] at a 12" depth. Your 20 long is about 12" deep but with substrate more like 10" +/-. Typically with that amount of light the tank would be considered 'high tech' dosing a full complement of nutrients and CO2 would be required.

Typically to resolve green water would be recommended to shorten the photoperiod but since this a 'work tank' lets try this. Here is my recommendation. Do your weekly water change (50% is good). Add a lot more plants to the tank to absorb the light and add more nutrients so the plants grow and thrive. Add a layer (maybe 2) of plastic window screen between the light and the tank to cut down on the amount of light and/or add some 'floaters' like water lettuce, red root floaters, or even duckweed to cut down the amount of light.

Three are also mechanical means to deal with green water, a Diatom Filter which uses diatomaceous earth can actually filter out the microscopic algae particles and keep the water clear, but diatom filters aren't cheap and not the easiest to use. Another option would be to use a UV Sterilizer to your filtration system that will kill off the algae that is in solution. Keep us posted on how it goes.
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OK, thanks. I will try those things and see how it goes.
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