phosban/alk issues

D

dolt

New member
I have been running two phosban reactors on my system now for two weeks and have two issues - one is that my phosphate is less than 0.03 but not zero - it was closer, but still less than 0.03 before so it has come down but not to where I want it - is it possible that it is already spent? this would surprise me a little as my levels were pretty low before and it has only been two weeks - I do not feed a lot and do weekly large (80-100 gal) water changes - is it possible that I had a large reservoir in rocks, substrate etc of phosphate that I am going to have to deplete?
the second issue is that my alk and calcium additions have greatly increased - I still use two part B-ionic (I am going to get a CR but have to let the wife simmer down from me buying a 1800$ skimmer first!) I used to add about 1.5 cups of each twice a day and now add 2.5 cups and still can not seem to get ca above 400 or DKH above 8.5 - I have read the article about this interaction and problems as linked elsewhere and it shed some light on the issue, but it seems like most people say this effect is short lived but does not seem to be for me
 
It is possible that it is "spent" if you did not use much, but more likely the ongoing additions and/or kit uncertainty are offsetting the GFO.
 
Bertoni - that was the article that I had read and refered to in my post (just did not have the link when I wrote my post) - I was wondering how long I could expect the effects on ca and alk to last? or I guess better put, what is others experience on the duration of this - from the article it appears that it is not clear if it is an effect of the lower phosphates allowing for better ca and alk consumption by corals etc or if it is more of a direct chemical effect of the media (precipitation on the media itself or adsorption to the media?)
Randy - I agree on the kit uncertainty business - I use the salifert and it seems to be less ideal for the lower range of the spectrum - the amount of "blueness" that I get is so faint that I have to compare it to the same volume of tankwater in another container to see if it is really there - but when I do there is a definite more blue color to the tested sample - one of these days I am going to have to spring for one of the more expensive phosphate test kits
 
I think the effect should last as long as phosphate is being removed from the water. If your tank reaches the point that phosphate input to the water column slows down, I'd expect the precipitation in the GFO to drop.

Likewise, once phosphate reaches low enough levels that the corals, etc, no longer suffer inhibition, that part of equation might at least stop growing. The coralline, for example, could become limited by other nutrients. How much you choose to feed will have a big impact.

For that size tank, you might want to switch to a less expensive calcium and alkalinity supplement, like a DIY 2-part or lime.
 
at what levels do phosphates significantly inhibit calcification of corals? my levels were less than 0.03 before I started using phosban, which is not perfect but not what I would consider very high either - I guess what I do not understand is that with fairly low phosphate levels to begin with why would it not remove all phosphate fairly quickly and also why would it positively impact calcification so much to go from low to very low - I do not think that lower phosphate inhibiting growth less would be the main explanation in this case unless my assumption on how much fairly low levels of phosphate inhibit growth - I do not feed very heavily - once a day about four times per week - I use about three cubes of sallys brand mysis shrimp and add one or two sheets of seaweed selects per week - that does not seem like much phosphate import and as above, I am a pretty aggressive water changer
 
at what levels do phosphates significantly inhibit calcification of corals?

It has a big effect at 0.2 ppm. Exactly how it impacts calcification as the levels drop from there hasn't been shown as far as I know.

This article discusses it a bit:

The Chemical & Biochemical Mechanisms of Calcification in Corals
http://www.advancedaquarist.com/issues/apr2002/chem.htm

from it:

"Another important issue has to do with the inhibition of calcification by phosphate and phosphate-containing organics. Phosphate is known to inhibit the precipitation of calcium carbonate from seawater.19, 20, 21 Phosphate also decreases calcification in corals, such as Pocillopora damicornis22 and entire patch reefs23 . This inhibition is likely related to the presence of phosphate in the ECF and on the growing crystal surface. Exactly how the phosphate gets in isnââ"šÂ¬Ã¢"žÂ¢t well understood. Nevertheless, the next time you are worried about phosphate levels in your tank, you can think of calcification inhibition in the ECF in addition to the driving of unwanted algae in your tank.

This inhibition of calcification takes place at concentrations frequently attained in reef tanks, and may begin at levels below those detectable by hobby test kits. For example, one research group found that long term enrichment of phosphate (2 mm; 0.19 ppm; maintained for 3 hours per day) on a natural patch reef on the Great Barrier Reef inhibited overall coral calcification by 43%. A second team found effects in several Acropora species at similar concentrations."
 
I do not think that lower phosphate inhibiting growth less would be the main explanation in this case unless my assumption on how much fairly low levels of phosphate inhibit growth

Besides increased organism calcification, the other effect is detailed in the article may be important in your case: the increased abiotic precipitation of calcium carbonate in the tank caused by soluble iron.
Do you see any such precipitates?
 
not in the tank - I do have a small coating in my sump where I add calcium but it does not really seem heavier than in the past as far as I can tell
BTW what is the molecule as your avatar?
 
BTW what is the molecule as your avatar?

It is phosphate, shown as PO4---. It is my favorite molecule, being not only important to reef aquarists, but one of my main tasks in my real job for the past 15 years has been to find ways to bind it in people. One of my drugs, Renagel, does that for patients on dialysis. :)

www.renagel.com
 
yeah, darned phosphate - it's a problem everywhere, when in excess isn't it? in people one of the concerns especially in renal failure (and the reason your product is needed) is the spontaneous precipitation of phosphate and calcium - I guess that that does not happen much in the aquarium system though because the phosphate levels are so much less? (but the calcium levels are so much higher in the aquarium system so maybe it does occur to some extent?)
I've got it! I'm just going to switch to renagel in my phosban reactor, I don't know why I did not think of this before!
 
the phosban is much cheaper per gram (0.07cents) with the renagel being about 1.75 per gram, but what is the relative binding capacity? I would suspect that the renagels is higher - BTW I am kidding but maybe there is something better out there to use (other than chaeto, which given my issues may be a better option!)
 
I've got it! I'm just going to switch to renagel in my phosban reactor, I don't know why I did not think of this before!

Actually, I tried it. It is a high capacity binder at the concentrations in the GI tract, but doesn't bind well at sub ppm phosphate levels in seawater. :D
 
that is pretty funny - I was just kidding - so I am assuming then if that is the best product on the market for medical use then there are no other better synthetic resins at least at this point that would work better than the GFO stuff we have now (conversely has GFO been tried in humans then if it is more efficient?) - as a side note I did start to get precipitation in my sump yesterday afternoon after trying to push up my calcium and alk - I guess it must be from the iron leaching out of the GFO that is causing me so much trouble - my DKH was a little high at 9.9 but I frequently have had it in the 9s with no problem - and my calcium was 415 which is not really pushing the envelope much - how efficient are refugiums with chaeto relative to GFO?
 
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