Themuleous said:
Hi All,
Ive got a very stubborn case on green water in my 20g. Ive run the UV steriliser several times over the last few months and it has cleared but it always comes back. Anyone got any tips?
I have reduced the lighting to 9hrs (2x18w freshwaters) would it be an idea to reduce this to 8hrs? Also I'm reduce PO4 to 1ppm 3x per week as I was dosing 1.5ppm 3x per week.
Thanks all
Sam
Hi Sam,
Sorry if I sound like a broken record but PO4 doesn't cause algae, ammonia does. :idea:
The reason that it returns is because of ammonia generation in the tank. Ammonia is being generated, possibly due to fish load and or inefficient filtration, but more likely because the plants are ill due to some form of starvation. Let's review compulsory dosing:
Gandalf's magic calculator says that a 20G ought to get the following:
3/16 teaspoon KNO3 3X per week
1/16 teaspoon KH2PO4 3X per week
Possibly 1/2 teaspoon MgSo4 3X per week (or pinch of GH booster once a week) depending on Mg available in tap.
1/16 tsp CSM+B (or 4 ml TMG) 3X per week
CO2 :?:...
These numbers can easily be doubled if you have high plant mass and/or high light. Is that 36 watts of T5 or is that T8? If that's T5 then it's quite a bit of light as the wpg rule breaks down at lower volumes. 9 hours is fine I reckon, but do the UV to get rid of it, water changes etc etc etc and rigidly maintain dosing.
We really need to break ourselves of the habit of suspending dosing when we get an algae outbreak. On the contrary when an outbreak occurs it's usually a signal that we ought to
increase dosing.
Also, what is your filtration and how often do you clean the filter? Detritus buildup in the filter breaks down and produces ammonia.
Cheers,