Is carbon (vinegar) dosing killing my macro algae?
 

Hi everyone,

I am new to this forum so please excuse me if I've posted this thread in the wrong place.

So, about a fortnight ago I attached a 25L DIY macro algae reactor to my 200L mixed reef aquarium. After researching macro algae reactors pretty extensively online, I was expecting crazy growth and nutrient export results. Although I think the algae has grown at least a little, I can't help but wonder if I'm doing something wrong. Nutrients have also stayed the same as usual the entire time.

Could my vinegar dosing be stunting the growth of my macro algae? I'm no expert but I'm sure vinegar would kill a garden plant, so why wouldn't it do the same to aquatic plants? I was formerly dosing 40ml daily of a 10% vinegar, kalkwasser, RODI solution, but stopped dosing two days ago now. Does anyone have any experience with this or know the science behind it? Did I do the right thing or should I continue carbon dosing? Thanks!

(Side note: Aquarium is 7 months old, phosphate is <0.25, nitrate is 10.)

Mitch,

I assume that you are operating a protein skimmer in conjunction with your vinegar dosing.

I do not subscribe to carbon dosing in a reef tank. Organic carbon feeds bacteria. The theory behind carbon dosing a reef tank is to remove organics, mostly in the form of bacteria.

All algae, coral zooanthelia is an algae, receive their carbon thru a process called
“carbon fixation”. Carbon dioxide in the athmosphere combines to form alkalinity, carbonate and bicarbonate. Alkalinity coupled with photosynthesis form glucose, the building block of organic biomass.

Drop the use of foam fractionation and quite feeding bacteria. Everything in your tank is competing for nutrients. Don’t encourage the wrong bacteria.

Other nutrients besides nitrogen & phosphate are required by macro. Iron is often a limiting factor. You did not say what macro.


Read what Russ Kronwetter says about macro algae on free info link at his website.

https://www.marineplantbook.com

Welcome Mitch. Generally, small quantities of vinegar dosed in a reef tank doesn't directly kill macro algae. It is just too dilute. Over time, the resulting low nutrient levels can slow or stop the macro algaes' growth, and even cause die off. You don't have that issue though since you report 10 ppm of nitrate & .25 ppm of phosphate. Inadequate light or flow, or lack of another nutrient like iron might be causing your problem.

If you haven't been dosing vinegar for long, stopping it would be ok. If you have been doing it for a while, you might slowly wean the tank off of it. Care should be taken when changing things in you reef tank though. Remember, nothing good happens fast in a reef tank.

Yes carbon dose can slowly kill macros like cheato. My question is why add an algae reactor when your no3 and po4 are already being controlled very well? 10 no3 and 0.25 po4 is not bad at all could come down just a little but I would not mess with it much. Have you tried slightly increase your carbon dose, water changes, tune skimmer to remove wastes faster? You only need a slight tweak to drop the no3 and po4 a little but to me added an algae reactor was chacing a non issue.

The acetic acid you are dosing ist calcium acetate, so, the comparison to acetic acid on a garden plant may not be a good analogy.

40 mL of vinegar will give you about 10 ppm acetate in your system. What isn’t known with certainty is the actual concentration. The prevailing assumption is that the daily dose is completely consumed before the next day’s dose. I have seen 0 science to back up that assumption.

Since you are carbon dosing to reduce phosphate and nitrate, why did you add an algae reactor? Just curious.

What is the issue or concern? Alga growth rate? Nutrient depletion rate? The system has plent of nitrogen and phosphorous for alga growth. What about light intensity, flow, and CO2 levels?