diatom mystery

[Reefs rule]

hi i have a wierd diatom problem. there are some diatoms growing on my sand and on one side of the wall. i use a power head to keep the water circulated. my phosphates are zero.
Water Parameters :

-nitrate 0
nitrite 0
ammonia 0

the tank is a 25 gallon nano reef with a clown fish and a neon goby. also, the power head is aimed at the place where the diatom is growing and the diatoms do not seem to be dissappearing.any help would be appreciated. i would definetly want to get rid of these nasty things.

[Reefland]

How old is the tank? Placing a poweerhead at the growth area is a deterant, not a fix.

[leebca]

If you have definitively identified them as diatoms then nitrates and phosphates aren't the main problem -- its silicates.

The shell of the diatom is made from silica (sand). In order for diatoms to 'rule' they need organics, dissolved silica, and light. Since they have no 'traditional' means of mobility, they sink. So, water circulation is important for their survival. Thus, more circulation, the happier they are. This is opposite to the needs of cyanobacteria (such as those that cause red slime in our aquariums) which don't get a good foothold with extra circulation.

Look for sources of silica in your water. That can come from source water; use of lubricating sprays in the home (i.e., Pam) that have a base of silica to help the delivery and reduce friction. There is a test kit by Salifert for dissolved silica.

And. . .BTW. . .Using sand as a substrate is NOT a source of dissolved silica, unless your pH is low. What pH range does your tank stay in?

[Reefs rule]

oh I see now. I thought that water circulation was the way to stop diatom growth. I havent tested my ph in a while so ill check it today. Also, i use RO water. Do you think that there is any silica in there? if so, how can I remove it?

[leebca]

The RO unit membrane may allow dissolved silica through. I'm unsure about the answer to that question. You might want to post that question in another forum or better still, you would have to check with the people who made/installed/sold/ it and/or the literature to find the answer to this one. Do you know if there is dissolved silica in the water being treated?

How did you determine you have a diatom problem? It might be a 'far-fetched' question, but by any chance are you using a skimmer on that tank?

Lastly, please answer Scott's question about the tank. How old is it? When did it finish the cycle?

[Reefs rule]

No i dont have a skimmer in my tank. i wish I could, but I dont have the room for it in the back of the filter. This is a 25 gallon nano cube, so there is limited room for those types of things. also i found out that the ph is low so ill see if the bufferer will fix the diatom problem. I am pretty sure that they are diatoms because they are brownish in color and can be easily be removed from the glass even with my fingers. Oh, and the tank is about 8 months old

[leebca]

What you most likely have is an indication of less than suitable water quality. There's more to water quality than just Ammonia, Nitrite, and Nitrate. You may want to read this: What is Water Quality

I think in the case of your aquarium, the cause is more likely water parameter control and nutrient control (i.e., too much organics).

When a system has matured these go away, unless the water quality is 'off.' ;)