Does carbon dosing increase or decrease water clarity?

Miami Reef · Jan 12, 2023

I read a few Reef Central forum posts about people saying carbon dosing improves water clarity.

However, I think I remember that someone said carbon dosing adds organics and slightly degrades water clarity.

Which side is the truth?

By saying “clarity,” I am referring to yellowing compounds.

dlsorensen · Jan 12, 2023

From my research and personal experience it has clarified the water. My skimmer has pulled more since I started dosing last week. I dose 5ml per day of DIY NOPOX for reference in my 125g.

Randy Holmes-Farley · Jan 13, 2023

I did not notice an effect, at least until the dose was so high the water was hazy with bacteria, but I also aggressively used methods to reduce yellowing (GAC, occasional ozone, etc.) before and during organic carbon addition.

srobertb · Jan 13, 2023

+1 to the yes….but actually no…

Personally I found when dosing correctly it worked to clarify the water. When I dosed too much, I got blooms.

I have upped my reefing game since then and my tank is far more stable and I have a better intuition about all of that so if I tried again I might do better but honestly I have found for water clarity activated carbon and a giant-sized UV sterilizer are much lower maintenance fixes.

I have brought out the UV sterilizer to combat a new-tank algae bloom and then again recently when I had to move everything to an emergency tank and it solved the cloudy issue both times permanently in around 48 hours- to the point that it looked like the fish are swimming in air.

I use carbon only when things “don’t look right.”

I will be hard plumbing the UV into a manifold on the new tank so it’s easy to turn on/off as needed.

Bearing in mind my water clarity issue cause may differ from yours but these solutions require (to me) less chemistry, measurement, and time vs dosing.

dwest · Jan 13, 2023

I’ve never noticed a difference.

Miami Reef · Jan 13, 2023

Randy Holmes-Farley said:
but I also aggressively used methods to reduce yellowing (GAC, occasional ozone, etc.)

How did you aggressively use carbon?

taricha · Jan 13, 2023

Many yellow compounds are byproducts of bacterial metabolism breaking down foods.
A couple of years ago got bacteria to take a clear solution and make really yellow water.
I started with a gallon of tank water, and did a tiny 0.05mL (salifert) scoop of ground fish flake + ~100ppm NO3 and a couple of ppm PO4. (something like F/2 media)
I split into 3 containers, bubbled all of them in the dark and gave
1 - nothing, 2 - Waste Away, 3 - Vodka

after about a week and a half, the least yellow was the one that got nothing. The Vodka and Waste Away bottles both got really yellow water after the initial cloudy bloom.

So sometimes a carbon dose can help bacteria make more yellow compounds. If I want to fight yellow water, I use the other carbon - GAC.

Miami Reef · Jan 13, 2023

taricha said:
Many yellow compounds are byproducts of bacterial metabolism breaking down foods.
A couple of years ago got bacteria to take a clear solution and make really yellow water.
I started with a gallon of tank water, and did a tiny 0.05mL (salifert) scoop of ground fish flake + ~100ppm NO3 and a couple of ppm PO4. (something like F/2 media)
I split into 3 containers, bubbled all of them in the dark and gave
1 - nothing, 2 - Waste Away, 3 - Vodka

after about a week and a half, the least yellow was the one that got nothing. The Vodka and Waste Away bottles both got really yellow water after the initial cloudy bloom.

So sometimes a carbon dose can help bacteria make more yellow compounds. If I want to fight yellow water, I use the other carbon - GAC.

You were the other side of the battle!

While I was writing this thread, I used the search function with your name because I remember you said something like this!

Thank you!