Dissolved Organic Compound

grantman · 03-06-2006, 09:00 AM

I did a search and it came up with no matches. What is a dissolved organic compound. Is it basically fish urine and coral waste?

drsyme · 03-06-2006, 09:04 AM

DOC's are the breakdown products of any organic item in the tank. Fish poop, food, detritus, algae.

Skimmers are great at removing them. DOC's are part of the import/export equation. You want to minimize the amount of stuff that goes in (food, bioload) and maximize your export (skimmer, water changes.)

tdwyatt · 03-06-2006, 09:04 AM

mostly, but will include the decompositional materials from left over food, coral mucus, fish mucus, daily cycling of algal biomass, etc. It is any material with a decent length chain or carbon or ring compounds that are dissolved in the water. As such, they will have some dipole moment and usually will have a polar end and a lipophyllic end. This makes them concentrate at the water/air interface allowing skimming to remove them as such.

tdwyatt · 03-06-2006, 09:05 AM

g'morning Jack, had some coffee yet?

Doug1 · 03-06-2006, 09:06 AM

Thats pretty much it, larger organic molecules that will attach to airbubbles, thats why skimmers do what they do, they dont remove dissolved elements directly, tho wet skimming will remove some salt with the skimate, but the nasty stuff in the collection cup is DOC

Doug1 · 03-06-2006, 09:08 AM

I guess I was slow on the draw

So who's posting under Toms name?

grantman · 03-06-2006, 09:08 AM

They concentrate at the air water interface. This may not be answerable but I will ask anyways. How fast do DOC's accumulate. I know it will depend on the system but if you have a heavily stocked system with fish and coral do these compounds accumulate very rapidly (like in hours) or does it take a few days for the air water interface to become saturated?

grantman · 03-06-2006, 09:09 AM

So who's posting under Toms name?

I was surprised at the brevity as well!!

drsyme · 03-06-2006, 09:45 AM

Quote:

Originally Posted by tdwyatt

g'morning Jack, had some coffee yet?

Morning Tom.

No coffee yet. Can you send some?

drsyme · 03-06-2006, 09:46 AM

Quote:

Originally Posted by grantman

So who's posting under Toms name?

I was surprised at the brevity as well!!

Maybe he hasnt had coffee yet.

Doug1 · 03-06-2006, 09:51 AM

Quote:

Originally Posted by drsyme

Maybe he hasnt had coffee yet.

grantman · 03-06-2006, 10:10 AM

Trying to get back on track. How fast does the surface accumulate DOC's assuming that no protien skimmer exists and it is a heavily stocked tank?

tdwyatt · 03-06-2006, 03:07 PM

a lot depends on how big (MW) the molecule is and how much of the chain is aoiphatic and how much is hydrophyllic (fat loving vs wawter loving in terms of olubility) as well as how uickly it is formed in the tank (how hevily you feed, how heavy your pops are, etc). There will not be a standard pat answer for this question, it will be much like asking "How many individual hairs do you have on your head?" ...and will vary from individual to individual. Expect there to be some accumulation every day, to the point that you will notice a film after 2 or 3 days. There is some biological removal as well due to decomposition of the DOC's by bacteria and due to absorption by organisms in the water column.

why would you not want to run a skimmer?

grantman · 03-07-2006, 06:42 AM

I will run a skimmer. I am wondering the most efficient way to skim the top layer of water. Geoff has a coast to coast on his tank. I can see how it will only take water from the surface, but will the entire surface be drawn through the ctc? Does aiming a powerhead or a return at the surface cause the DOC to accumulate elsewhere? I have a prizm deluxe with the surface skimming attachment but I am sure that it doesn't draw water from the entire length of my tank.