I'm ADDING Phosphates, and my Nitrates are going down!

[Bill S]

Ha! I believe it's working. I added enough PO4 last Thursday to bring my PO4 up to about 0.75ppm (no, not 0.075), using what Richard, Mark and I believe to be sodium biphosphate (from Hiatt). A big pinch in a 215. Slowly, it has been tracking down, and yesterday it was back to 0.0. My nitrates have gone from 20+ to around 12-15. Added a smaller pinch last night, and we're back up to around 0.25ppm.

P.S. DON'T DO THIS IN YOUR TANK. For those that don't know, I'm running a Hiatt carbon filtration system. The jury is still out on this though...

[TheOtherGuy]

Hey Bill that is cool. I am doing some interesting things in my tank also. I will tell you my experiences later. No time right now.

[Bill S]

Just an update. I added PO4 for the THIRD time last night. Still going to zero after about 4 days, and NO4 are slowly coming down. Very weird...

[TheOtherGuy]

Awesome. What are your latest readings?

[Bill S]

Well, tonight NO4 is back up to 15-20ppm. PO4 is only 0.10, after adding PO4 24 hours ago... I'll probably add some more on Tuesday. Everything else is pretty much OK, my Alk is down a bit, so I'm going to fire up the CO2 on the Ca reactor in the am. Ca is 550, Mg is 1400, pH is 8.1. Also in the process of my weekly 28 gallon water change. Still, everything seems to be fine, except that the SPS isn't thriving. The LPS SEEMS to be growing again...

[GaryP]

Bill,

If I may I'd like to make a suggestion. Rather then dosing the PO4 in a batch process as you are doing now, why not drip it in. That would help prevent the wilde swings in PO4 levels. The extremely high levels after a treatment are probably causing some problem with your corals. I personally would prefer to maintian a constant level around .1-.2 ppm that would be closer to that of NSW. I think that would be better for the Hiatt too so that its activity can remain more constant.

The other thing I would suggest is that you borrow one of the German meta phosphate kits. I think Todd and NaCl_H20 have one. I would like to see what the background organic phosphate level is in the tank. The bacteria in the Hiatt are probably chewing it up as well. PO4 doesn't hang around long in a rapidly growing bacterial culture. For this reason alone I have considered incorporating a wet/dry into my next system. I think the demise of the wet/dry in most systems is one of the main reason why we see high PO4 problems and the resulting nuisance algae issues. Of course this assumes that bacterial biomass is somehow harvested and exported from the system. For this I plan of building the wet dry with a floss filter on the bottom as well as the one on the top that most units have. That will at least capture the larger chunks of bacterial biofilm that are sloughed off.

I realize this is a little off topic. I am talking about reducing PO4 while you have the opposite problem. Your's is a classic case of ecological limiting nutrients. I'm having to think back to a class in microbial ecology I took a long time ago. Growth, and in your case, metabolism will only be maintained to the point that the limiting nutrient is used up. Both nitrogen and phosphate are required for growth and metabolism. Once the PO4 is used up, the bacteria basically shut down, or rather slow down, and are no longer able to metabolize the nitrate. Bacteria store energy on an intracellular basis in the form of organophosphates such as ATP and ADP. The phosphate bonds in these molecules are extremely high in energy. My first job out of school was in developing quantitative tests for bacterial concentrations based on measuring ATP levels photometrically with the enzyme that comes from fireflys (luciferase). Luciferase utilizes ATP as its energy source for the bioluminescent process. We used this test on industrial waters so that we didn't have to wait for culture to grow out. Some of these bacteria are very slow growing and as you probably know, a single culture media will usually only grow out 10% of the bacterial species present, at best.

[Bill S]

Gary, the drip idea is a great idea... Maybe I should just add it to my topoff container? It's a bit large at 30 gallons, but if I see the PO4 getting too high or the nitrates drop too much, I can just drain it. I'm evaporating about 4 or 5 gallons a day.

[GaryP]

That's an option. Just figure out what your weekly phosphate demand is and add that much DSP to the make up water. From your original post it looks like you would need to add somewhere around 175-200% of what you added to get the 75 ppm residual in order to supply the phosphate at a rate that is close to the demand rate for an entire week. As I recall you went from 75 to 0 in arond 3-4 days. That means your daily demand is around .15-.20 ppm. That's sorta hard to believe, but, the old rule of thumb was that you need a 4:1 ratio of nitrate: phosphate. Since you have an excess of nitrate right now, perhaps that is reasonble. In addition to that you are getting the contribution of the phosphate from the food. Of course you are also getting nitrates from that too and perhaps its just a break even. I would suggest starting at one dosage and do some testing to confirm that you are dosing at the proper rate. If the PO4 level is still 0, increase it until you get a .1-.2 residual. If you are building a PO4 residual, cut it back. I don't think you will need to dump your top off tank, just add more water to it to dilute out the PO4.

Do you fill the top off tank in a batch process or is it set on a seperate cut off valve on your RO unit? If it is continuous, remember that you will need to be constantly adding more PO4 to it to maintain the concentration. If its batch, just re-dose whenever you re-fill it.

[GaryP]

Man... All it takes is a little microbiology, biochemistry, and chemical engineering talk to chase folks out of a thread in a hurry. I wonder why that happens. :) That's OK, you and Ace still understand me. My sole consolation.

[Bill S]

The top off has a float valve in it - but I'm not all that trusting of it, so I usually turn it back on every 5-7 days or so to fill it back up. I could easily do that. I'm going to measure it again tonight, and then I'll do some calcs to see if I can nail this down.

Richard was over picking up some seahorse babies. He thinks the tank is too clean - it looks kind of sterile. But he seems to think I'm feeding OK. I've also noticed that my sump filter is really not getting dirty at all, like it used to... He took a sample to run some of the more obscure tests, to see if anything (doesn't) show up.

[Ram_Puppy]

-- Rampuppy runs screaming from the chemistry like a little girl --

Gary the topic killer. :)

very interesting reading for a HIATT n00b.