Phosphate in NSW storage

Tbell805 · Dec 1, 2017

Hey there reef chemistry people!
I am fortunate to live by UCSB where they have a source of saltwater for the public. My question is lately I've been dealing with phosphate in my reef. I'm winning the battle just tested .02 and .03 on hanna phosphorous checker the past two weeks. I had to replace HC gfo weekly and occasionally use phosphate rx to get to this place though. These are just bandaid fixes though and I wanted to find the cause. I tested the water that I get from UCSB and store in a brute trash can and it was at .1 ppm! I get 30 gallons at a time and do 10 gallon water changes weekly on my 90 gallon reef so the water sits at a maximum 3 weeks. In my efforts to keep stable parameters I was wondering what the best way to lower phosphates in this stored water would be. Typically I let it sit in the brute and about an hour before I turn on a pump and circulate it before pumping it to the tank. No heater and no circulation the rest of the time. Would tossing in a bag of gfo pull from the water without it circulating? I also wonder if I could place a pump inside a filter sock and dose phosphate rx and then remove the sock. Let me know your ideas I look forward to hearing them!

saltyfilmfolks · Dec 2, 2017

I'd get that test checked. Nsw should not be that high.
I'm just down the coast , and I can show you the triton test someone did.

Randy Holmes-Farley · Dec 2, 2017

Might be from organisms dying in it (if accurate), but even 0.1 ppm in top off water is not really a big deal. You add way more in foods and that is the "cause"

I discuss it here:

http://www.advancedaquarist.com/2012/3/chemistry

Comparison of Food Sources of Phosphate to Other Sources
What about other sources of phosphate, like the "crappy" RO/DI water containing 0.05 ppm phosphate? A similar analysis will show it equally unimportant relative to foods.

Let's assume that the aquarist in question adds 1% of the total tank volume each day with RO/DI to replace evaporation. Simple math shows that the 0.05 ppm in the RO/DI becomes 0.0005 ppm added each day to the phosphate concentration in the aquarium. That dilution step is critical, taking a scary number like 0.05 ppm down to an almost meaningless 0.0005 ppm daily addition. Since that 0.0005 ppm is 40-600 times lower than the amount added each day in foods (Table 4), it does not seem worthy of the angst many aquarists put on such measurements. That said, tap water could have as much as 5 ppm phosphate, and that value could then become a dominating source of phosphate and would be quite problematic. Purifying tap water is important for this and many other reasons.

Tbell805 · Dec 2, 2017

That is peculiar. I'd be interested in seeing that triton test. The next time I get water I will bring my hanna checker and do the test straight from the source to see if it is low and is indeed die off. Thanks Randy for that link to your article it is full of good information. I'm glad I don't have to worry to much then about adding this water. It is a blessing to not have to make my own salt water.