Cyanobacteria and pH issues. help.

Well, this is the first time i've ever really freaked out about algae.

some quick info.

20g H, 70w MH 14k, HOB Filter (biowheel type), No protein skimmer, LR & LS. tank is 8 months old.

so for about a month or so i've been dealing with an increasing cyanobacteria problem.

Also haven't been able to keep pH under control (keeps going back to 7.7)

pH 7.7
Alkalinity is 12 dkh (I wish it was 8, but i have to keep adding pH UP to try to stabilize pH)
Nitrates 0-0.5ppm
Phosphates 0 ppm
Cal 440ppm
Mag 1330ppm

All these levels have been pretty constant throughout the life of the tank since about 2 months in with very little tampering by me.

uggh, it's driving me crazy, my tank is starting to get covered in the red slimey cyano... i had a big bloom about 2 weeks ago... thought i had it under control, wiped it off all my rock...

Then, it slowly starts coming back, then it comes back FAST.

I'm tired of looking at my tank like this, i feel like i'm losing the war here.

I don't get what's causing it, my flow could be a little better, all i have is a koralia nano powerhead... but i've had the same powerhead for the life of the tank and never had this problem except VERY early on (2nd month) and i just let it bloom and die off and haven't dealt with it since.

I've been feeding less, my fish seem agitated by this... What is an appropriate feeding schedule for a 1.5" Regal Tang, 2" Maroon Clownfish, and 1.5" Six-Line wrasse?

The problems seem to have started since I added the tang, he does eat like a mad-man and steals all the other fishes food.

But, like i've said, i've been cutting back on feedings, phosphates/nitrates are zero and still the problem persists. I wonder tho if the cyano is just intercepting the phos/no3 as it forms... so it is just very quick at assimilating them? could this be it? if so wouldn't i see some big die off?

Tried some big water changes. NO CHANGE IN ANY WATER PARAMETERS.

my tank just wants to be at 7.7 pH with tons of cyanobacteria no matter what I do to change it.

What am I missing here?

I plan on adding a 10g refugium under the tank with a 4 or 5" LS bed and some chaeto... maybe this is the answer?

 

When you say you cut back on feeding what type of feeding schedule are you on?

 

Well, first of all your nitrates and phosphates are probably much higher. If you are having a bad algae issue you have to throw results for those tests out the window. The problem is that the algae (in the case bacteria) consume the nitrates and phosphates faster than what can be tested, giving you a false positive.
So lets do the usual checklist. Feeding what and how often? Water change schedule? Water source? How much rock? Have you taken the wheel portion of your filter off? Maintenance schedule for the filter?
Then there are three problems I see with what is existing with your system. The first is no skimmer. That's not going to be good for the nitrates. The second is not a single one of your fish belong in a tank that small. That's a lot of extra waste that a 20 gallon system just can not overcome. The third is that PH-up is a freshwater additive. Who knows whats in it in regards to alk, PO4, etc. That is most likely what is making it tough to balance your ph/alk.

 

i think u nailed it. too much bioload. protein skimmer and 10g refugium here we come.

i feed just enough so each fish gets a flake or two, 2x a day. occasionally give vit enriched brine shrimp (every 3 days) instead of a flake meal and tenera blue for tang

 

2x a day? im currently winning a fight with cyano and ive been feeding every other day just to keep it down until i get total control of this cyano. please correct me if im feeding to little for this scenario.

 

Try getting rid of the cyano and increasing your pH. That should help.

 

2X a day? Wow! I feed on Monday and Thursday. Fish don't need as much as they want.

 

I have a question, not being sarcastic ...

He's got 3 fish that are each less than 2 inches long. Did I read that right?

Are you saying that he cannot have a single 2 inch fish in a 20 gallon tank now, or that he will be overloading after the fish grows???

Seems to me that 3 of 2 inch fish are ok (if he had the right kind of filtration), but probably not ok once they're full grown?

 

updates, ive added a prot skimmer but its only been 3 days and no skimmate yet.

ive reduced feedings to eod and giving the tang (six line likes it too) tenera blue and trying to selectively feed the maroon just a little bit eod

yeah the fish are all babies except for the six line. the clown and tang will outgrow the tank, especially the tang... but in the mean time they have plenty of space and all get along beautifully.

cyano still spreading.... just keeping it off the corals at the moment, tomorrow i am setting up a fuge with a live DSB and chaeto and using an eheim classic for my return pump.

so i think with all that extra filtration and dsb and macros as well as skimmer the cyano should go away. pH is creepimg back up (7.9-8.0) last i checked

 

I like SeaChem Reef Salt, it's PH is 8.4 and priced great.