DOC Goldie Locks Level

[TbyZ]

Activated Carbon is very effective at removing Disolved Organic Compounds from aquarium water.
Too much DOC, not good.
Not enough DOC, not good.

What would the typical signs be to indicate that too much DOC has been stripped from the water in relation to coral health?

 

[Randy Holmes-Farley Verified Community Expert]

I'm not actually sure, nor do I even know if the premise is correct (at least, whether corals suffer in reef tanks from, say, too little DOC without creating some sort of extreme case).

 

[TbyZ]

I'm not actually sure, nor do I even know if the premise is correct (at least, whether corals suffer in reef tanks from, say, too little DOC without creating some sort of extreme case).

At the very least DOC is bacteria food. Could a low bacteria count affect corals directly?
Corals eat bacteria also. Could this be a problem?

I don't know, but I have read, & watched vids where hobbiests suggest over use of GAC has negatively affected their corals.
Do you believe, Randy, that removing DOC from the water column to the point where only trace amounts remain would be near impossible?
Thanks for the response.

 

[TbyZ]

Anyone else here noticed any connection between heavy use of GAC & negative coral health?

 

[sghera64]

Anyone else here noticed any connection between heavy use of GAC & negative coral health?

Yes: ROX 0.8. Filled the canister about 1/2 full and within a week, my Goniopora started to shrivel and torches P.E. was reduced. Water looked a lot nicer, but I don't dwell "in" my tank so my vote doesn't count. I cut back the flow through the carbon canister and things returned to normal after a month. I don't recall my SPS suffering, but I have pretty basic species (purple tipped cerealis, subglabra, green slimer/staghorn).

BTW, how does one measure DOC? I added ulva to my sump about 4 weeks ago and put a 100W LED grow light on it. The algae has completely taken over the sump and my NO3/PO4 are undetectable (Red Sea Pro / Hanna ULR). Corals look just fine (SPS and LPS). I just read on R2R today that algae can rapidly remove these basic nutrients + CO2 + light and convert them to sugars, amino acids, etc. My understanding is that the algae I added just keeps the nutrient fly-wheel going and I'm now unable to measure what's in there. So, I have to use coral health to gauge.

Thoughts?

 

[TbyZ]

Yes: ROX 0.8. Filled the canister about 1/2 full and within a week, my Goniopora started to shrivel and torches P.E. was reduced. Water looked a lot nicer, but I don't dwell "in" my tank so my vote doesn't count. I cut back the flow through the carbon canister and things returned to normal after a month. I don't recall my SPS suffering, but I have pretty basic species (purple tipped cerealis, subglabra, green slimer/staghorn).

Thanks, & interesting. Had you been using rox prior to this? Maybe it was a case of stripping DOC too quickly?

BTW, how does one measure DOC? I added ulva to my sump about 4 weeks ago and put a 100W LED grow light on it. The algae has completely taken over the sump and my NO3/PO4 are undetectable (Red Sea Pro / Hanna ULR). Corals look just fine (SPS and LPS). I just read on R2R today that algae can rapidly remove these basic nutrients + CO2 + light and convert them to sugars, amino acids, etc. My understanding is that the algae I added just keeps the nutrient fly-wheel going and I'm now unable to measure what's in there. So, I have to use coral health to gauge.

Thoughts?

No test kits for TOC or DOC.
The algae needs nitrogen & phosphate too grow. If you cut it back & remove it from the tank your basically nutrient exporting.

 

[sghera64]

Thanks, & interesting. Had you been using rox prior to this? Maybe it was a case of stripping DOC too quickly?
No test kits for TOC or DOC.
The algae needs nitrogen & phosphate too grow. If you cut it back & remove it from the tank your basically nutrient exporting.

Removal = nutrient export: I totally get that. What's weird is over the 4 weeks of growth I've had there is ALOT of algae. If I were to completely dry that algae, I'm of the opinion there would be more mass than the amount of dry flake food and even frozen food (if I would measure dry weight) I have fed over the past month. Is that possible in the initial months of setting up an algae fuge?

 

[Randy Holmes-Farley Verified Community Expert]

Anyone else here noticed any connection between heavy use of GAC & negative coral health?

I've not seen a lot of information on this, and it certainly could be important, but reducing DOC a lot will also reduce some trace elements a lot (since some are strongly bound to organics), clouding the interpretation.

 

[TbyZ]

Removal = nutrient export: I totally get that. What's weird is over the 4 weeks of growth I've had there is ALOT of algae. If I were to completely dry that algae, I'm of the opinion there would be more mass than the amount of dry flake food and even frozen food (if I would measure dry weight) I have fed over the past month. Is that possible in the initial months of setting up an algae fuge?

I'd like Feldman to do an indepth analysis of the filamentous emerald green hair algae growing in my scrubber.

 

[Randy Holmes-Farley Verified Community Expert]

Removal = nutrient export: I totally get that. What's weird is over the 4 weeks of growth I've had there is ALOT of algae. If I were to completely dry that algae, I'm of the opinion there would be more mass than the amount of dry flake food and even frozen food (if I would measure dry weight) I have fed over the past month. Is that possible in the initial months of setting up an algae fuge?

It's possible, certainly. It all depends on the nutrient density of the algae vs the foods, but I'd be surprised if it is actually true in this case. Algae contains a huge amount of water and if you dry it out, it will take up a much smaller size.