Reef nutrition

Carbon and phosphate media how often u change?

[Standard Gresham Groggy Disclaimer]I thought the the phosphates came from the phosphoric acid they use to activate/clean it? [/SGGD]

I do run carbon actively, in an old phosphate reactor (that rhowaphos/powerphos stuff is too damn expensive!) and usually when it clogs up with gunk, couple weeks, I replace it, because I'm sure the gunk probably is working against me at that point more so than the carbon is leaching back into the tank.
 
Dunno which is worse, but IMO both aren't good :) (either detritus leaching or GAC leaching)
 
Maybe I should go back to passively running it, so less detritus gets sucked in. If anything I recall when I did do that it became a nice little hideaway for various pods, but I felt silly trying to save them all when removing the old stuff and yeah I tried to save them...
 
I'm the same, I don't comb the cheato that I throw out but I try and flick any fat pods back into the sump before I throw the stuff out.
 
[quote author=sfsuphysics link=topic=3827.msg44752#msg44752 date=1212685595]
[Standard Gresham Groggy Disclaimer]I thought the the phosphates came from the phosphoric acid they use to activate/clean it? [/SGGD]

I do run carbon actively, in an old phosphate reactor (that rhowaphos/powerphos stuff is too damn expensive!) and usually when it clogs up with gunk, couple weeks, I replace it, because I'm sure the gunk probably is working against me at that point more so than the carbon is leaching back into the tank.

[/quote]If your worried about phosphate, take a couple of fresh granules and do a phosphate test with them in the vial, if there is no reading your good, it's phosphate free. At that point since (as Gresham pointed out) carbon does not adsorb phosphate it should not leech phosphate, DOCs on the other hand, carbon will leech when exhausted.

If I service a tank that is pretty yellow from end to end, I'll run a ton of carbon active, and have the customer pull it after 3-4 days that way the water is polished, and the carbon hasn't been in there long enough to leech.
 
Dissolved organic carbon.

I run a 300 micron mesh in between the pump and the material so the pods don't get in there.
 
300µl won't help 25-45% of the life cycle of Tigger-Pods (depending on growth factors) and about +90% of what we normally have in our aquaria (typically Tisbe sp.). Where did you get 300µl would stop pods from getting in?
 
Wasn't referring to something as small as tigger pods or anything smaller. Was referring to the larger amphipods. I could care less about the smaller stuff. :p
 
so....GFO. 1g/gallon. What is the density of this stuff lol.

I picked up the high capacity GFO and will need to use 40g for my 40g according to their instructions...I have no scale lol.
 
lol. I may have to but until then, I want to get an approximation :p


is 40g like 1/8 cup? Don't make me bust out GFO partical packing densities.
 
I dunno with the high capacity, I'd do it like a drug dealer. Know what the over all weight is eyeball it, cut it in half, cut the half in half and continue until you get the desired proportion. I run extra in my reactor in case I get lazy, I haven't seen any detrimental results.
 
My first post! Thanks for the add BAR, finally get to hang with the cool kids ;)

But back on topic:
[quote author=GreshamH link=topic=3827.msg44579#msg44579 date=1212518098]
Both depend on you PO4 and DOC load. They could be used up in a day if high enough, or last a year if low enough. You can't tell what your demand is going to be off of some one else's tank, you just can't.
[/quote]

My line of thinking as well. I use a 1/4 cup every two weeks personally on my 50 :)

Im wondering though, are you sure we(as a collective) are not confusing "leeching out" with merely exhausted carbon unable to soak up the ever increasing normal day to day DOCs build up to detectable and/or high levels? I think it would be harder to test definatively then you might think.
Ya, you can take it out of the tank and let sit in some "clean" SW, but you would have to make special care, you couldnt just plop the whole bag in as you would be testing positive for DOCs that were trapped/suspended in the mesh bag. I think the only way to get good results to confirm leaching would be to take it out of the bag into a container and some how VERY GENTLY rinse/stir to remove and suspended organics stuck to your wet clump of carbon, then take the carbon and put it into another "clean" sw container for soaking and testing...No, yes?

-Justin
 
Hey Justin! Welcome to BAR! :D

I'm thinking the same as you regarding leaching. Also, I don't see a massive outflux of stuff from the carbon if water quality has been kept reasonably stable with water changes.

Worse should be that the carbon reaches an equilibrium with the water as far as DOC. It's concentration gradient plus affinity to the carbon that drives movement of DOC in one direction or other.

DOC movement from carbon to water might happen if there was a bunch of carbon in really dirty water for a long time followed by massive water changes.
 
Now wait, did I say MASSIVE influx? You can debate what I say, but you can't put words in my mouth AND debate me :D

Carbon has been around far longer then anyone on this forum, or their grandparents (and their grandparents, etc). It's been around a long time in other wrods. The fact it can leech back out over time IIRC has been shown in many tests over the years (need to find references for you). The test is very basic and doesn't require an aquarium. You simply put a known amount of a chemical that can be taken in by carbon, place it in with the carbon, remove carbon and place in clean water...test. Yah, there's probably some washing or something as well, but that's the basic idea :)

I'll pick Randy, Boomer and Bob Starks brains...I'll get some references for you from them :D
 
[quote author=GreshamH link=topic=3827.msg46233#msg46233 date=1213803673]
Now wait, did I say MASSIVE influx? You can debate what I say, but you can't put words in my mouth AND debate me :D
[/quote]

Yes we can, and you will LIKE IT!!!
The test is very basic and doesn't require an aquarium. You simply put a known amount of a chemical that can be taken in by carbon, place it in with the carbon, remove carbon and place in clean water...test. Yah, there's probably some washing or something as well, but that's the basic idea :)
Click to expand...

Gresham, what you just described can EASILY be predicted using very fundamental chemistry. In fact, it is a basic principle called Le Chatelier's Principle which describes equilibrium.

Here comes a little chemistry lesson for those not familiar with it. You will see that the leaching is incorrectly interpreted in the test you described.


The reaction of waste removal can be approximated by

Junk + Carbon --> junk-carbon
(where the junk is somehow adsorbed onto/into the carbon by non covalent bond means)

It really isn't a one way reaction, but is rather reversable
Junk + Carbon <--> junk-carbon

This process has a mathematical relationship

constant = (concentration of junk in water ) * (Available absorption sites on carbon) / (filled carbon sites)

This is grossly simplified but that is ok.

THis equilibrium constant is just that. A constant. The "junk" will move to one side of the <--> (equation) to satisfy this constant. If you were to measure those values and find that the constant is not equal to the equilibrium constant, then the system will shift. Pretend that the measured value is high (ie, it wants to be lower. This is the normal aquarium situation) To satisfy the equilibrium, you need to increase the numerator (which also decreases the denominator). This means junk goes from the water and into the carbon. This will happen until there is proper BALANCE.


Balance is the key word (ie equilibrium). So when you take carbon saturated in junk, and place it in CLEAN water, you ruined the balance and junk leaches out. This is NOT the same as normal leaching. People see the word leaching and think that the carbon fills up, then the carbon dumps the junk into the water. What ACTUALLY happens, is carbon fills up and then it is just in equalibrium and junk in the carbon exchanges with junk in the water. This happens slowly and on a long time scale. If you have nothing else to soak up junk yet you are adding more junk into the tank, the levels of junk increases and you have this "OMG, my carbon is leaching!" when really you have "OMG, the trash cans are full but I am keep trying to put more and more trash in them"

This lession is brought to you by the letter E
 
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