Phosphate

[JoshsReef]

i have always had phosphate problems with my tap water, it was the main reason I bought an RODI unit. Anyways my fresh batch of sw, mixed with rodi water, is still testing at 0.5 phosphate just like my tap water always did. Could it be the salt mix?

I am thinking about ordering new test kits, currently i use red sea, which test kits are preffered ?

[Ziggy953]

What kind of salt mix do you use? It could be that you got a bad bucket. It does happen. Test the phosphates of the RO/DI water before you add the salt and see what you get.

[JoshsReef]

same thing , rodi water 0 tds = 0.5 phosphate. I cant figure it out, the only thing i can think is that it has to be the test kit, or maybe somthing in my rubbermade containers. Im using Reef Crystals

[Ziggy953]

I use reef crystals too. Collect some water in a glass container and test that. If you keep getting the same results I would get another test kit and see if it comes up with the same numbers.

[melosu58]

Maybe you can run a sample to your LFS to double check your results.

[Kurt_Nelson]

How old is the DI resin in the RO/DI unit? If possible, get a sample after the RO stage but before the DI stage and see if phosphates are showing up there. If there's none before the DI stage, but it shows up after... bingo - you need new DI resin. Depleted DI resin can actually leach contaminants back into pure water.

I'm having doubts that the 0.5ppm reading is accurate though. That's a LOT. I'd definitely get a second opinion or test kit and verify. I use, and like, the Salifert Phosphate kit. Good ability to read down to very low levels.

[MsBeanCtr]

I have fought continually with my phosphates in my tank. I tested, re-tested, tested some more etc. I would definitely take Kurt's advice and check into your resin. Also, I found that my test kit was junk and when I got a good kit I got completely different readings.

Also, be sure to rinse your frozen food VERY well before feeding it to your fish.

Good Luck!

[JoshsReef]

The rodi unit is brand new, so it cant be bad di resign. Im ordering a new test kit this evening, I seem to doubt that I could have that bad a phospate problem straight out of a brand new unit. Thanks for the help, I think Im going to splurge on the salifert tests !!!

[Kurt_Nelson]

I wouldn't say it couldn't be the resin, but I agree with you... it's more than likely the test kits. Especially if you're reading 0.5 out of your tap. That's pretty darn high.

Just FYI... from my understanding, DI resin that isn't sealed against air can get depleted over time from the CO2 content in the air. Depending on how the DI cannister has been stored while waiting to be sold, you might not be starting out with a "full" charge. I've often wondered about the quality of the stuff in some of those bargains on eBay. Not sure if that's your case, but just putting it out there for something to consider.

[Ziggy953]

I agree with you Kurt. The ebay store I ordered mine from shipps the DI and the RO Membrane in pre-sealed packages. The DI resin was even vaccum sealed. I was very surprised.