Who runs the simplest system here?

[Scrubber_steve]

Originally Posted by Turtlesteve

Yeah, but.... there's also no evidence that the DOC/TOC spike differs in composition from the baseline (he goes into great detail about how difficult this is to measure). Your counter-suggestion would imply such a difference.

You are correct that he doesn't directly claim that the bacteria can handle everything, as it wasn't tested in this article - but it's still a reasonable inference from his work. Consider some of the follow up work:

https://www.advancedaquarist.com/2009/1/aafeature2/

Taking all of this together, it is pretty certain to me that protein skimming is a minor, supplemental method of clearing DOC's. If bacterial activity in a skimmed tank processes 65-80% of the total system load (in DOC's), it's reasonable to infer that a modestly higher bacterial population could handle all of it.

Also, burden of proof should be the other way around. I'm amazed at how well stuff sells in this hobby just because someone uses it on a tank that happens to house high end SPS. I have a skimmerless tank and two working skimmers sitting on a shelf. I might use them again one day when I'm convinced I need one.

Steve

Feldman made the observation that systems that don't
purify the water via GAC &/or skimming have doc levels far higher than natural reefs, (so bacteria doesn't do the job!) & sensitive corals don't do well in systems that don't use GAC & or skimming because of this!

[Turtlesteve]

Originally Posted by Twinfallz

Feldman made the observation that systems that don't purify the water via GAC &/or skimming have doc levels far higher than natural reefs, (so bacteria doesn't do the job!) & sensitive corals don't do well in systems that don't use GAC & or skimming because of this!

I'm aware of one tank with no GAC/skimming that he sampled. Were there more sampled since? Even if the above were correct, he also tested a skimmerless tank with GAC and it was low DOC - so should we assume that GAC can functionally replace a skimmer? I don't necessarily believe this either.

I suspect that there are other important factors controlling DOC levels.

Steve

[Scrubber_steve]

Originally Posted by Turtlesteve

I'm aware of one tank with no GAC/skimming that he sampled. Were there more sampled since? Even if the above were correct, he also tested a skimmerless tank with GAC and it was low DOC - so should we assume that GAC can functionally replace a skimmer? I don't necessarily believe this either.

I suspect that there are other important factors controlling DOC levels.

Steve

GAC removes up 80% of DOC compared to a skimmer at 35% max. I don't skim, just GAC.
But if carbon dosing, a skimmer is part of that inorganic filter method

[brian3]

For me simple was the only way I had success. I tried all the additives, kalk, you name it. Finally stopped all additives completely and have an 2 gal / day automatic water change from a tank in the basement I mix up in a large batch and I do run a skimmer. That is it. Growth has been great and going on 20 years the tank has been up and running. No hair or slime algae for years, only some bubble to contend with. Over the years I failed miserably when I tinkered and tried the latest and greatest additive or snake oil.

[Turtlesteve]

Originally Posted by Twinfallz

GAC removes up 80% of DOC compared to a skimmer at 35% max. I don't skim, just GAC.
But if carbon dosing, a skimmer is part of that inorganic filter method

OK, I re-read through Feldman's articles on GAC and skimming - he stated that two unskimmed / no GAC tanks were tested and both were high in DOC. While not conclusive, I'll concede it seems likely that something more than biological filtration is needed to run low DOC.

For what it's worth I'm running GAC at the moment, but have not been all that consistent with it.

Steve

[Scrubber_steve]

Originally Posted by Turtlesteve

OK, I re-read through Feldman's articles on GAC and skimming - he stated that two unskimmed / no GAC tanks were tested and both were high in DOC. While not conclusive, I'll concede it seems likely that something more than biological filtration is needed to run low DOC.

For what it's worth I'm running GAC at the moment, but have not been all that consistent with it.

Steve

It really is beyond argument that skimming, & especially GAC remove dissolved organics from the water.

How much, & how little doc is best for sensitive corals is the question. If we could test it as easily & as accurately as say alk what numbers would be targeted?

[Turtlesteve]

Originally Posted by Twinfallz

It really is beyond argument that skimming, & especially GAC remove dissolved organics from the water.

...But that point was never being argued. My position is:

- Skimming is not the primary method of DOC removal in skimmed tanks.

- Therefore, there must be other significant methods of DOC removal in skimmed tanks that run low DOC. One method is GAC as you've pointed out - are there others?

I do agree with your point about sensitivity of corals. Maybe it's time someone develops a hobbyist test kit for DOC...

[reefgeezer]

There are not a lot of methods to address DOC. A few organisms may be able to use DOC but being "dissolved" limits its availability to most organisms and many mechanical filtration methods. There are however many organisms that can limit DOC by using/exporting organic matter in the particulate stage... before it dissolves. Sponges, corals, clams, scallops, and the like can have a big impact on DOC & reduce the need for skimming or GAC.

My tank is still not mature but I keep it as simple and efficient as possible... DC pumps, LEDs, bare bottom, dry rock, skimmer, ATO, and a little GFO. I used to carbon dose and add nitrate. This has become unnecessary as the tank matured. I think possibly GFO will be the next thing to go. My skimmer & ATO however, will always be employed. It just doesn't make sense not to use a few watts of power for the benefit received.

[Fourstars]

I found the analogy that we can consider TOC's as "the soil of the seas". Interesting way to look at it. I spend a lot of time Enriching the soil in my garden, but not to much, as I don't want to burn the roots or add to much salt.