Diatoms That Just Won't Go

theKoolAidMan · Mar 30, 2019

My Reefer Nano is about 5 months old now. In that 5 months I have been pretty much unable to get past what seem to be diatoms coating EVERYTHING in the tank. It gets on the glass, rocks, and absolutely coats the sand. It looks like a bag of brown flour exploded on everything.

At first I thought this was just the ugly phase, as I've gone through this with other tanks, including my Reefer 450. However the diatoms just never went away. About one month ago they seemed to start to disappear on their own and I started to get green algae growing and my PO4 levels started to slightly rise, so I added some GFO. This stopped the green algae but the diatoms returned with a vengeance.

I do weekly 20% water changes on both this tank and my bigger Reefer 450. The 450 has no issues with algae or diatoms, so I don't think it's an issue with the RODI water.

Any ideas? Pics below. Nitrate and Po4 are basically undetectable on my crappy API tests. The one pick makes it look like a cyano-like film, but in reality it is powderly. If i blow it with a turkey baster it doesn't come off in globs or sheets like cyano but rather like grains of flour.

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EmdeReef · Mar 30, 2019

Can you take pics without the blue lights on? That may not be diatoms.

theKoolAidMan · Mar 30, 2019

Here you go. It's very brown. Also, there is a video if it helps. Again if I blow it with a turkey baster it comes off like powder.

VIDEO HERE

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theKoolAidMan · Mar 31, 2019

I should add that at night they almost completely disappear, only to start returning when the lights are on. By the end of the day it looks like it was snowing brown snow all day.

Dimmy007 · Mar 31, 2019

I would say those are Diatoms. Right on schedule with about how old your tank is. I wouldn't be to worried.

https://www.reef2reef.com/threads/is-my-cycling-done.409370/reply?quote=4846160

Scurvy · Mar 31, 2019

I have the same problem in my Biocube. About the same age. Setup in late Oct, Early Nov. I also used black sand and am starting to believe this to be the issue. Its the only thing different between this setup and every other tank Ive built. Diatoms are usually long gone by now for me.

Dimmy007 · Mar 31, 2019

Dinos are more of a slimy texture. The way they are explaining it as a powder to me says diatoms. I think if you want to know for sure get a microscope and that should give us the answer for sure.

theKoolAidMan · Mar 31, 2019

Scurvy said:
I have the same problem in my Biocube. About the same age. Setup in late Oct, Early Nov. I also used black sand and am starting to believe this to be the issue. Its the only thing different between this setup and every other tank Ive built. Diatoms are usually long gone by now for me.

I was reading some other threads on this forum and others and some believe do believe that the black sand had higher levels of silica as it is not an aragonite sand like white sand. The diatoms just feed off of that silica and never seem to go away. Eventually they will subside but it may take a LONG time. I'm considering changing out the sand. I've already removed most of the corals and put them in my Reefer 450, so it won't be hard to do.

Scurvy · Mar 31, 2019

Yeah, I have read that as well. I might remove my handful of corals and try running a bunch of GFO or Phosguard to see if I can pull out the excess silicate. I really want to try black sand and a ZOA/LPS tank for the contrast to black.

Scurvy · Apr 3, 2019

FWIW I did pull my corals and added a fist sized bag of Phosguard over the weekend. Diatoms are fading fast. Not really sure how long I'll need to keep it in there but it seems to be working for the short term.