Phosphate Information that Changes Everything

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Phosphate Information that Changes Everything

Welcome to my first blog on the new Lighthouse Aquatics website. I've been on a phosphate rampage as of late. It all started a few month ago when my supplier was out of my regular phosphate test kit. I went with a more expensive brand from Salifert and to my surprise, all of my tanks were testing high in phosphate. I wondered how this could be. I've always used phosphate media in all my tanks, except freshwater. What I discovered has changed everything I thought about water chemistry, and changed the way I test and maintain all my tanks.


Well I couldn't find a simple definition, so in a nut shell phosphate is a byproduct of the food we feed our fish. It acts as a fertilizer. Algae love it, and when not controlled, nitrates rise and algae will soon destroy your beautiful aquarium. Phosphate is like a poison to coral and coralline algae as it interrupts with the calcification process (Simkiss,1964; brown et al 1977). Phosphate averages around .03ppm from reefs around the world. A phosphate of .3 ppm can have a damaging effect on our reef aquariums.


I'm a service guy, and my passion is reef aquariums. Having low nitrates or low nutrient levels is always a constant battle in the aquariums I maintain. After realizing most of my tanks were testing between .5 to 1 and up, I quickly double up on the phosphate media. What I found was, as the phosphate was nearing the .25 & .05 range, the nitrates were dropping as well. I try to maintain reef tanks under 10ppm and fish only under 20ppm. I was able to drop nitrate levels without changing anything in my normal service. I just started adding more phosphate media and changing it more often. The results were 5 and ten point drops in nitrate. I have a couple of heavily stocked fish only tanks fed only frozen foods with constant 70 ppm nitrate. I was able to get a 30 to 40 point drop in nitrate in both tanks. Keep in mind, I service these tanks 2 x month and do a 20% or more water change, plus cleaning the skimmer, all filter media, and vacuuming gravel etc. I'm now adding phosphate media to my freshwater accounts and seeing similar results. I do a lot of research and reading and have never read about a correlation between nitrates and phosphates.


My favorite is GFO or granulated ferric oxide. Brand names like Rowaphos an Phosban work very well. Buy a good quality GFO. There is a difference if its too cheap, skip it. I like Seachems Phosguard, but found it had trouble pulling high phosphate down quickly. They're both very easy to use. Add media to a 300 micron bag, rinse and put it in your sump, canister filter, or better yet, a phosphate reactor. Just do it, and test often! Please follow manufacturs sugestions on grams per gallon. Too much at one time can impact alkalinity.


Please don't skimp here. I've used two brands lately. Salifert and Elos both work great. There are many others out there, but I just haven't tried them yet. To sum it up, having accurate testing is vital to maintaining our aquariums over the years. I've taken many calls from tank owners who stated their aquarium was fine for the first 6 month and then all the sudden this algae appeared and they been unable to get rid of it. Phosphate builds over time. For that reason, I always add phosphate media to all new aquarium set ups. Until next time.

Image courtesy of EMSL,