Red Slime algae... HOw do i get rid of it?

I keep my lights (250 wat MH+96watt PC) on 9 hours
there is a lot of flow in the tank
I use RO water bought at the water store
Nitrates =0
*I have done a 20 gallon water change (75gallon tank+20gallon sump+10gallon refugium)
This red slime stuff is everywhere. especially under the metal halide light which is on the left side of the aquarium.
I'm going to get some of the seachem phosphate filter stuff. and use as directed to get the phospates down to 0.
Anyone have any other advice?


Active Member
How often are you feeding? I beleive the main cause of cyano is excess nutrients. You metion that you have good flow but do you have good flow in that particular area where the algae is. You might want to cut back on some lighting time too until you get the algae under control. How old are your bulbs also? And get those phosphates down which you are already planning on working on.
So, to alleviate some of the excess nutrients should I do a few water changes. I'm going to do 20 gallons today, and planning on another 20 on sunday or monday. The flow on the gravel (which under the halide is covered with the cyano) is pretty good and the flow hitting most of the rockwork is good too. The side without a MH light dosn't have as much algae. So, maybe my bulb is not good anymore. I wouldn't be suprised. The fixture i bought off of ---- was a generic piece of poop!


I agree with Mr. DC, you should cut back on lighting or change your bulbs if they are old. Cyano is a versatile algae that will use photosynthesis, and feed off of nitrates, phosphates etc. to grow.
Cut back on feeding and liquid organic additives.
Some critters eat Cyano. I have a Halloween hermit that is know to eat cyano. Other crabs will as well.
If you have lots of cyano, the best thing to do IMO is remove it by hand/with a syphon. Stop flow in the tank to prevent slime from spreading while cleaning. Scrape with one hand, syphon in the other hand.


Active Member
Originally Posted by florida joe
actually it is not an algae at all but a bacteria
I've been reading "Red Slime Algae" on the forum for the last week. I couldn't figure out what was going on, when i started up my first tank, I had a Cyano-bacteria spike, and I learned from that experience that it was a bacteria. I just thought there had been new developments i didn't know about, lol. If I remember right, its not photosynthetic either....right or wrong?
Just throwing this out there, when I had my spike, I was told to purchase Miracin, or something like that. Its a freshwater fish medication for gill rot or gout or swine flu, i dunno. i was told to use one capsule per day per 55 gallons, and to remove all cyano that i could daily. within a week, it was all gone, no light schedule changes, just water flow. did a water change two times in one week, and i was back in business in no time. I had that tank for 3 years, after that first issue, i never saw it again.


Well-Known Member
There are two times IMHO you get cyano. Once during the initial cycle which goes away as the tank settles in. And the more serious bloom several month later.
Cyano is a bacteria with plant life in it. Like all forms of plant life it needs nitrogen, phosphat, potassium, co2, and light. Most plant life (corals, algae) in our tanks uses ammonia/nitrates for nitrogen. But cyanos have the ability to get its nitrogen from the dissolved nitrogen gas. So after a few months it is possible for the tank (and algae) to become nitrate limited which allows the cyano to bloom.
fortunately the cyano grows fast and dies fast. So the simpliest thing to do is to kill the lights. Which will return nitrates to the system and allow the algae to be in control again.
So my advice is to kill the lights for a few days.
my .02


Well-Known Member
Also you could check the phosphate reading of your RO water before you add it. One of my LFS's has old membranes and I get a phosphate reading off of their RO water every time.


"Cyanobacteria thrive in low circulation, poorly aerated conditions. " I would check for those things first. The whole nutrient thing is little too simple. It takes a bit more than just having nutrients in the water. Cyanobacteria photosynthesis uses carbon dioxide and water, releasing oxygen as a waste product. With extra nutrients as bob stated above, it will spread quicker.


Active Member
over many years of this hobby i have had my share of this stuff.imo i think it is like bealsbob said.usually in a young tank 6 months or less.i have never found messing with the water gets rid of normal water changes and suck it out.once the tank matures it will go away and pretty fast .i havnt noticed any difference in reducing light .imo time gets rid of it as long as you do the regular maintanance.