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Re: Green Water
On Tue, 29 Feb 2000, Steve Pituch wrote:
> I tried changing the water, against
> the recommendations I've read here, and the phosphates in the tap water
> cause the algae to return full force in about 4 days.
The phosphate by itself isn't the problem, but one way to take care of
that part of your problem is to run your tap water through a phosphate
absorber before you use it in your tank.
> I tried my diatom
> filter that cleared the water up to 50 % visibility, but the green returned
> soon after I removed the filter. I don't want to wait it out as my plants
> are slowly dying from lack of light. The fish are doing quite well.
A diatom filter should take it out. You can help your filter along by
adding a flocculent to make the algae cells bunch together.
> The parameters of the aquarium are.
> 75 gallons
> PH 7.0 directly from the tap. Goes to PH 8.2 without CO2 injection. When
> the water is really green the PH creeps up to about 7.4. This is with about
> 4 bubbles per second CO2.
> KH=220 ppm
> GH=110 ppm (?)
> Phosphate=.5 ppm
> ammonia, nitrite, nitrate = 0, but I have tried 15 ml TMG with 1.5 gm K2NO3,
> same results.
> lights are currently two 175 MH pendants.
This is quite a bit of light for a 75 gallon tank and it may make the tank
unusually prone to green water. This is particularly true for a new tank
where the plants aren't yet well-established.
One method of getting rid of green water is to leave the lights off and
cover the tank for a few days. The floating algae can't live long without
light, so after a few days you might have clear water again. Some people
claim this works without damaging their plants. When I tried darkening
one of my tanks it *definitely* set some of the plants back, and the green
water came back afterwords anyway. But it works for some people.
> temp night = 75 deg f, end of light period 78 deg f. duration = 10 hours.
> I just read that someone was successful using a diatom filter. I have an
> XL. After about a day, the diatom mixture was pale green, but the water
> would not clear past 50%. I also read in Innes that potassium permanganate
> will clear green water. I don't want to hurt the plants, nor fish.
> I was thinking of using an additive to get the PH down into the low sixes.
> I think the CO2 injection can't help below 7.0 because of my water hardness.
pH is not a part of your problem. If you add something now you're more
likely to make the problem worse than to make it better.
> There is no surface algae anywhere in the tank thanks to 2 SAEs, 4 CAEs, and
> 2 small plecos.
> Any advice would be appreciated. I just want to get over this so I can grow
My most dependable solution is to add a flocculent and filter the algae
out. That alone could solve your problem *if* all that's needed is for
your plants to get established and competitive. If not then you will need
to look for and fix other problems that are favoring the algae.