Constant diatoms in 1 year old tank.

[Kassh4815]

So I have had this tank going for about a year, 55 Gallon African Cichlid tank, stocking is around 13 mixed mbuna and peacock 2 loaches. Recently my Yellow tail ACEI had babies so I have to get them out soon. My issue is I have a lot of mountain rock in my aquarium and I keep having a massive amount of diatoms form and I have to remove and wash the rocks every two weeks. This gets a bit of a pain in the rear, and I was wondering if there was something I could do. You can see in the pictures where its forming on some (this is my first aquascape so be gentle)

Water parms are 0 ammonia, 0 nitrate, and nitrites I try to keep under 10 PPM but goes up to 20 every so often.
2 75 gallon HOB filters,
1 (undersized) UV filter
1 heater,
2 low power wave makers were added to try and keep diatoms off rocks (not working)
Changing water 1-2 times a week at 75 percent.

 

[Demeter]

Tank looks good and fish look healthy, having a bit of algae growth is normal. I have it in my own African tank (not so much anymore as I moved a BN pleco into it). I would almost suggest a pleco but mbuna are probably the worst ones to have with plecos.

Your best bet is to reduce the lighting but I personally wouldn’t fuss over it much, if anything it gives to tank a more natural feel to it. Now if it was covering the glass, then I might be a bit more annoyed!

 

[A201]

The Mbuna likely eat most of the green algae, which allows the diatom to flourish.
Washing the rocks not only removes algae, it removes the coating of benificial bacteria, which is not a good thing.
Both my tanks are full of algae eating fish. The rock hardscapes are covered with diatom. IMO, it gives things a more natural look.

 

[FishDin]

I assume the picture was taken after you cleaned, as I see no diatom problem.

Nerite snails keep my African tank clean. They love diatoms. And work incredibly fast.

I don't think diatoms give the tank a natural look. Well, maybe natural, but not very pleasing. I find that when every piece of hardscape (including the sand) is a dull brown color, the tank becomes very dim and not very nice to look at. Because African tanks are often stuffed with rocks, most of the tank can be covered in diatoms. I agree that a little touch of diatom here and there would be fine and of little concern.

In my 55g African tank, diatoms appear, but they don't stand a chance to last more than a few days. I have 4-5 Olive nerites in the tank. However, with the small amount of rocks you have, one or two would be plenty.

Without plants, your light is only there for viewing. Decreasing the light intensity and or duration will help as well. If you can't dim the lights, I'd decrease the time they are on. Use a timer so that it's only on when you are home or want to view it. The fish don't need bright light. How long is the light on for? I'd start with 6 hours a day for a while (a month?) and see how things go.

I would stop cleaning the rocks for the reasons mentioned above.

EDIT: I used to clean (mechanical scrub only) my rocks as well, when I had diatom problems. I would do 2-3 rocks with each water change so that they all would not be done at the same time. But, yeah, that can get tedious.