Cyano? Diatoms? Help! See pic.


I don't know if this is Cyano, Diatoms, but it is a pain!!! I've also recently started getting some green hair algae which you can see in the top middle right where my middle powerhead is blowing. I've got 3 powerheads (one in the left corner, middle and right corner all blowing towards the center). I haven't changed lights in about a year but am holding off for Metal Halide which I am expecting to get in about a month.
I have included a picture where you can see it coating the live rock, sand, and glass. I only use R/O water, levels are all perfect. Have heard about the ChemiClean chemical but really don't want to go that route....are my powerheads in the wrong positions? Lights too old? I don't think it is from overfeeding as I have about 60 Nessarius snails, 2 brittle stars, and some hermit crabs to take care of the extra I only feed about once a day.
Any suggestions? Lights are on for about 10 hours a day....should I have them on less? 220 watts on a 75 gal tank. Stuff easily scrapes off but comes back in about a week....I can "fan" it off of the live rock and it sheets off.


Just scraped the glass clean....but it will come back in a few's some more pics...close ups and look at the algae infested powerhead!



do you make your own Ro water or buy it from somewhere. either way id test the quality of water wherever your getting it and test your tank and RO water for phosphates.
it sure looks like cyno to me with an explosion of hair algae
id get some more clean up crew, check/change filters for RO if your make it yourself. get new bulbs or upgrade to the metal halides that you are wanting, and follow instructions on this post it should help. Good luck


Have own R/O system and have changed filters recently.....3 weeks ago. Lights are now off! THANK YOU for the link!!!! I will follow that step by step and will update on progress.....I thought my lights were only on 10 hours a day and I checked and they are set for 12 hours a day! I think that may be part of the problem.....I'm killing the lights for 36 hours.


Active Member
Do you have a protein skimmer running? How often are you doing a water change? In my aggressive tank, my lights are wayyyyyyy old. I used to have that problem but it went away after some good water change to lower down the nutrient levels. It's all gone and it have not come back at all, it's been over a year later now. Those stuff are mainly caused by excess nutrients and phosphate. Need to get those in check!!! :happyfish


Active Member
Yikes thats a lot of cyano and makes me feel bad about complaining about the occasional patch or two in my system.
Manual removal at this point, although a hassle, would be my first step. Siphon off whats on the sand bed. You will probably lose some sand but if you rinse it out well and let it dry in the sun it can be replaced or just replace with new. Maybe even taking the sand bed down to where its just a thin layer covering the tanks bottom for now. Nutrients caught in the sand bed could be a major contributor to your problem. It appears there is enough rock in the system to maintain bio filtration so I would not worry about the reduction in your sand bed although it may be a good idea to monitor ammonia and nitrite levels
All of this is going to constitute a lot of water changing so it looks like your off to the LFS for the economy size salt bucket.
During one of the larger water changes you may want to siphon water into a tub and clean off your rock manually in it also. Yep more hassle. The power heads can be cleaned up in tap water.
Its obvious the tank is not over stocked so the likely nutrient source is your feedings. You could easily bring down your feedings to once every two or three days and just enough for each tank occupant to get just a mouthful. There does not appear to be any corals in your tank so a drastic temporary reduction in lighting could occur here also. Maybe just lighting the tank on days you feed and for no more than 4 hours or so.
If your not running a skimmer or have one that is not producing the problem will likely continue. The ASM skimmer line will give you the best bang for the buck IMO.
I would also avoid the temptation to use any product like Red Slime Remover when this much cyano exist. The die off of this amount of slime would constitute a significant threat to overall water quality. If after you manually remove all that you can see this product will kill off any that is left and at least give you a fresh start but use of this product is always a last resort and is hotly debated as to any problems it may cause. 90 percent of those that use the product report good results but if the original source of the nutrients that caused the problem to begin with are not addressed the cyano will eventually return.
Good luck and in a situation like this perseverance is the key. Eventually you will get it straightened out.