Algae??

[Beej1254]

So lately I've been battling high nitrates and did a 20% water change then 10% every other day for about 2 weeks. My water is clearing up and levels are returning to normal. I've also had a problem with sunlight hitting my tank through a window that I just now covered. I also built a counter current protein skimmer that is now producing dark green skimmate. I'm reducing feedings per day down to only twice a day. I've still got this gunk on the rock that was hit by direct sunlight for the majority of the day. Any ideas what might help fully eliminate this?

[likeaboss2645]

What do you have in your tank that needs to be fed twice a day?


90 gal reef

[alyxandria]

I would say it is likely the amount you are feeding. Are you feeding frozen or flake? If it is frozen then make sure you are rinsing it first.

In the saltwater hobby some feed every other day and many even feed every three days. You want to feed just enough for the fish and not enough to add too many excess nutrients into the water.

[Gregcoyote]

You don't have to reduce the interval your feeding, but reduce the portions. Algae in new systems is inevitable. I prefer to have fat fish and reduce my algae issues with things like water exchanges, GFO, Purigen and/or a ATS. The sunlight can be a issue as it has algae producing (lower frequencies) light present. But in the simplest of terms, it's a balancing act between nourishing the fish and eliminating excess left over nutrients.

Be sure your using pure water when you mix your salt.


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[Beej1254]

I usually try and give small portions and watch my fish eat. I'll cut it back some but I'm worried they won't get enough. I feed flakes in the morning and a cube of frozen either mysis or brine at night. I'll admit I never rinse or thaw the cube it just goes straight in. I'm also wondering if I should turn off my sump return so nothing drains into my sump and sits there instead of getting eaten by the fish

I'm also hoping blocking out that sunlight will help. during peak daylight hours the sun light can get pretty intense on the front portion of my tank.

I'm also using RO/DI water that I make in 20 gallon batches of saltwater. I however don't have a TDS meter so I can't say how great the unit works. That'll be next on my list of items to buy.

[Beej1254]

I'm also hoping the skimmer will help

[Gregcoyote]

It will!


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[Beej1254]

Quick update for anyone..I'm still looking for some guidance. This slimy black gunk is gone from all my rocks which is great. BUT I still have patches of it in my sand that seems to shrink after lights off and then come right back when lights on. I'm feeding my tank once a day now and my phosphates are reading 0.0 - 0.25ppm. I can't really tell on the color card for the api test kit. it looks more like 0.0 to me. I've actually missed the last 4 days of feeding because I was in the hospital and came home to green water. I thought the problem was ok and resolving itself until a power head fell off the glass and blasted my sand everywhere. I always gravel vac my sand when doing water changes but I'm wondering if I had trapped nutrients? I HAD a decent clean up crew until I added 10 blue leg hermits....big mistake.

any help on how to rid my tank of this gunk is well appreciated.

[Sniperhank]

It's cyanobacteria. Thrives in nutrient rich water and low flow areas.

[Gregcoyote]

Sorry you were in hospital, that sucks!

Just remove it and as mentioned, increase flow to the areas it concentrates in and keep up the water exchanges, it will slowly go away.


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[Beej1254]

Thanks guys! I got some new saltwater mixing now.