I cant beat this one on my own.

[aquaph8]

Ok, I have what I believe is Diatoms. Its a brown dusting on my sand bed that goes away if you stir it up. It started during a couple of changes to my system. First, I have 4-48in vhos and I switched from 2 super actinics and 2 actinic whites to 3 actinic whites and 1 super actinic. Second, I stopped using the water from the water machine at my local convenient store (which never caused any algae or any other issues before) to making my own water with a RODI from BRS (should be better). The TDS meter reads 0 and I keep up with all maintenance on the system. I have a hard time blaming my RODI water and I would think silicates wouldn't be a problem. Could my lighting change cause this? If its the lights would it last this long? Its been almost 3 months. Any tips or info would be really appreciated and please ask any ?s that would help in the diagnosis with this problem.:confused:

[sowellj]

How long has the tank been up and running? Any somewhat recent changes in bioload?

[aquaph8]

Almost 3 years
nothing too big

[sowellj]

Well, if it is diatoms, they should just go away. But, it is a bit strange that they just appeared in a tank as established as yours. Verify that your RO/DI is plumbed correctly. Are you sure it is not dinoflagellates?

[outy]

well it could be silicates fueling diatome if it is.

if it is run alumina based phos remover and it will pull silicates out

in a tank 3 years old i would suspect silicates, happened to me on a 14 year old reef, ro/di read 0 but silicates still go through. replaced my di resin and its all gone now after running alumina based phos remover

[Paco]

Clean your circulation pumps. In my experience the diatoms and stuff start showing up as my Tunzes get a little slower due to build up on the intake screens. I pull the intake screen and vinegar then every month or two and it really helps.

[aquaph8]

I know, all the years I used less than perfect water and never had an issue. No I'm not sure its not dinos. I'm positive about the plumbing but I'm not sure if I should trust the TDS meter. I don't have any issues with any livestock, its just ugly. I'm doing weekly water changes and keep vacuuming the sand and its back the next day.

[aquaph8]

Outy, i will give it a shot. I clean my pumps often. Thanks for all suggestions.

[bertoni]

You might be seeing any number of types of microbial pests. There's usually a bit of silica in salt mixes, so that might support a bit of diatom growth. If you're seeing diatoms, snails will eat it. Dinoflagellates and cyanobacteria can be a lot more trouble. In any case, I'd work on nutrient control. A GFO reactor is a common approach, as is improved skimming. The tank might be getting too much food, as well.

Some people go with carbon dosing, although I'd try some of the other remedies first, because they seem less risky, based on people's comments.

[aquaph8]

Jon, I've been carbon dosing for a while now. I'm also running a gfo reactor from BRS.

[bertoni]

Well, I'd check some freshly-mixed saltwater. If you want to risk the aluminum binder, it's easy to remove it.

[aquaph8]

Will do, thanks for your help. I'm gonna steer clear of the aluminum binder for now. I will be sure to check out the new salt water.