Bacterial bloom with carbon dosing

saltyhog · Dec 6, 2015

I've been carbon dosing for about a year now with vinegar. It has worked well with nitrates being reduced from about 20 to 1-2. Unfortunately I had a big bacterial bloom with white mucous in my overflow, the sump and some on the rocks. My SPS took exception to this and I lost a couple of colonies of acropora that I had been growing for a couple of years. I was dosing about 100 ml of vinegar/day at that time.

I stopped for a while when that happened but my nitrates have gradually risen to about 10 so I started dosing again. I'm up to 50 ml/day dosed in to the fuge section of my sump (a little live rock and chaeto). Unfortunately I'm seeing some of the white mucous looking stuff returning. If I turn my return pump off for maintenance the stuff comes out of my pipes when I turn the pump back on. Is there any way around this problem?

Tank is 72x24x21 with a 40 gal sump. Running GFO and carbon in reactors. RO/DI with 28-32tds in and zero out. Fish stocking : 6 wrasses, copperband BF, pyramid BF, pair of black ocellaris, royal gramma and a Randal's goby/shrimp pair. I feed about a silver dollar size section of LRF a day. Skimmer is appropriate size (Skimz SM203).

Newb73 · Dec 6, 2015

I would begin looking for other sources of carbon getting in to your tank such as via aerosolized etc.

When i tried biopellets i got bacterial blooms. I find i can keep my nitrates down fairly low with frequrent water changes and running both CAC and GFO and changing the filter socks every 3 days. and keeping my skimmer at 100% effieiency at all times. Heck i even skip changing my socks and some times let my reactor go a while just to try and get the nitrates UP a little....

Downbeach · Dec 7, 2015

That's a sign of too much dosing, I would cut back the amount to the point where you're not getting the excessive bacterial growth. How much skim mate are you getting out of your skimmer? How often are you changing your GAC? Have you tried cutting back on your feeding?

Randy Holmes-Farley · Dec 7, 2015

How are you adding that 50 mL per day?

saltyhog · Dec 7, 2015

In 4 doses of 12.5 ml by dosing pump each hour for 4 consecutive hours in the evening. My thought was to minimize the pH impact by splitting the dose during the time of highest pH.

Randy Holmes-Farley · Dec 7, 2015

Spreading it out into more, smaller doses over a longer time might be useful (allowing more to be used in the refugium and less left over for elsewhere). Is there much substrate/rock/sand/media in the refugium for bacteria to grow on?

Reducing the flow through the refugium might also help.

That said, with a lot of hungry bacteria already in place elsewhere, you might need to get rid of a lot of it somehow before you can get other types growing in less obvious places (such as on rocks or sand).

Switching to a different type of organic (such as vodka) may also help.

saltyhog · Dec 7, 2015

There are just a few pieces of Tonga branch rock and cheato in the fuge. How would I get rid of the "other" bacteria? I thought I had read that the bacteria types aren't necessarily different with different carbon sources?

Would changing to biopellets in a reactor help or does the bacteria primarily grow outside the reactor?

Randy Holmes-Farley · Dec 8, 2015

saltyhog said:
There are just a few pieces of Tonga branch rock and cheato in the fuge. How would I get rid of the "other" bacteria? I thought I had read that the bacteria types aren't necessarily different with different carbon sources?

Would changing to biopellets in a reactor help or does the bacteria primarily grow outside the reactor?

I do not think anyone has identified what species grow in reef tanks with organic carbon dosing, but switching from one source to another may well drive different species.

Manual removal or a UV filter are probably among the best ways to remove the existing visible bacteria.