Gunk on sides of tank - Diatoms?

[gbose]

So I've been suffering for months from a build-up of brown gunk on the sides of my tank. It starts literally a couple of days after a cleaning. I thought it was algae and went nuts trying to bring my nitrates and phosphates down. Didn't succeed and still have it.

Now I'm thinking diatoms. All I've been able to find by reading is it may be insufficient light. Does this make sense? I have two 30Watt LEDS about 5-6 inches above the water of my Red Sea Max 34G...

Please let me know your thoughts. Would like feedback before I go looking for new lights...

Thanks!

 

[vetteguy53081]

Likely diatoms. As tank cycles, it will become less and less. Diatoms are a brown algae that typically appear in a reef tank that has just completed its cycle but they can also appear in an established reef tank. They can cover sand, rock, pumps, glass, you name it. Diatoms look ugly but in most cases they are harmless so the key is to not panic when they appear.
Diatoms feed mainly off of silicates but also consume dissolved organic compounds, phosphate and nitrates. Unfiltered tap water can contain silicates and is a good way to jump start a bloom if you use it to mix salt or to replace water that evaporated from the tank. The best way to prevent this from happening is to filter water through a RODI unit, although you can still get a diatom bloom when using RODI if the cartridge that removes silicates expires.
diatoms are typically harmless to a captive reef and can be beaten once their food source expires. Once you put the kibosh on the source, the outbreak should last a couple of weeks so just be patient and it will pass. For major outbreaks you may want to consider the three day blackout. Diatoms are easily wiped from the glass with a mag float, a turkey baster or a toothbrush can access other areas of the tank. Be prepared for them to re-establish themselves quickly, they are likely to be able to resettle and have exponential growth rates.
To prevent their return, practice good aquarium husbandry by doing regular water changes, keep the substrate clean, don’t overfeed the fish, ensure your skimmer is running at an optimal level and rinse out filter socks and sponges on a regular basis.
Some cleaner crew to help control it are : Cerith snails, Nerite snails and Trochus snails and also Astraea snails are effective at removing diatoms.

 

[gbose]

Thanks, Vetteguy. I only use RO and salt water from my LFS in my tank, and it's fully cycled (I've ahd it 10 years)

I'll try the 3 day blackout. Thanks for suggestion!