# Diatoms in a mature tank?



## RainSong (Jun 30, 2011)

I have a 90 gallon planted tank (rather heavy fish load) that has been up for over a year. I have been seeing a lot of "dirt" settle on my leaves and substrate and float around the tank. I thought it was BBA but think it might be diatoms. It does not respond to H2O2 at all and rubs off easily with my fingers.



















If it is diatoms, I assume this is due to high silica either from my tap or from the rocks in my tank (substrate is ecocomplete).










Does this make sense? Should I take out the rocks? How do you test your tap for silica?

Or am I just waaaay off base here ....


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## oscarsx (Mar 15, 2011)

I had a few outbreaks in a well established tank before, I believe it was because I did some re-scaping and stirred up the substrate a bit.. that gave me a nice diatom bloom..

Did you do something similar recently? Maybe cleaned out your canister filter?

- Oz


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## RainSong (Jun 30, 2011)

All of the above!

I keep escaping trying to improve things. I cleaned both my canister filters thinking this would help with cleaning the suspended "dirt".

Should I just chill out for a while?

Sent from my SGH-T999 using Tapatalk 2


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## RainSong (Jun 30, 2011)

Can someone please confirm if what I have looks like diatoms?

Thanks!


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## Kyrol (Feb 24, 2012)

Looks like it. I get it from time to time normaly at seasons change only thing I could figure was it's something to do with the city water supply.


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## accordztech (Dec 6, 2004)

I had experience with diatoms with my established tank. I was running top soil under silica sand and people were convinced it was my sand. But I tried many things to remove it, even purigen and it was temporary...

I noticed that in the shadded regions of the tank I didnt really get diatoms to show up, but in the areas where light was hitting I definitly got them. Tom kept saying its something with the co2 and light. So I bumped the co2 and noticed no changes. Then I decided to turn off one of my t5ho's...low and behold the diatoms started going away.

Till this day, I dont have any diatoms with my silica sand. 

http://www.plantedtank.net/forums/showthread.php?t=137425&highlight=diatoms


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## RainSong (Jun 30, 2011)

I contacted my Water District and was told that the tap water contains 5.2mg/L Silica. Is this high, medium or low?


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## Alplily (Jan 1, 2012)

Glad for this post as I am having the same diatom trouble in a 35g well-established tank. Perhaps I should turn the lights off for awhile... very frustrating.


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## reiben (Aug 18, 2012)

Did you disturb the substrate? Released ammonia from substrate is often the cause. After every re-scape, you need to change at least 50% of water.
Secondary, diatoms are often in tanks with too much light and not enough CO2 supply. So cut the lights down or increase CO2 supply (or both).


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