Testing for Phosphates?

[KingRicky]

Can you use a standard saltwater phosphate test kit to test RO/DI water? I am having trouble with lots of algea, my phosphates always test 0, was told that the RO/DI water could have Phosphates if the filters were dirty. I purchase my RO/DI water from my LFS. I want to test the water before I mix in the salt.

 

[GMaquarium]

Hanna photometer is a much better way to test po4

 

[stunreefer Verified Sponsor]

You can use PO4 tests for slatwater to test your RO/DI effluent, however Hanna photometer is the best by far as mentioned (most liquid tests are total BS).

It is true that RO/DI can have PO4 present in it.

 

[Paul_N]

Hanna photometer is a much better way to test po4

I agree, most tests will show zero when it is near 1 and we are looking for .03.

 

[AZDesertRat]

If a good handheld TDS meter is registering 0 TDS on the RO/DI then phosphates should be pretty much undetectable.If you can test the RO/DI with a conductivity meter thats even better since it is more sensitive. Most places that sell bulk RO/DI commercially have a conductivity meter. I know the Water & Ice stores around here all have conductivity meters.

Phosphates like silicates are weakly ionized so it takes good DI resin and contact time to get them all. If a RO/DI is not well maintained it is possible from them to get through but it will usually be indicated as TDS at which time you would change DI resin and check RO rejection rates.

 

[KingRicky]

Thank for the info. I am battling a bad hair algea problem and am trying to eliminate the cause. all parameters test normal. I have been told that Phosphate will test 0 due to algea using it to survive. What could be causing the algea outbreak if not phosphate?

 

[AZDesertRat]

Nitrates can also test 0 or low in the presence of algaeas.

I would look at circulation, direct lighting like sunlight, types of foods, feeding frequencies and amounts, any filter floss, socks or sponges that can be trapping detritus, etc. It almost always is not the water since a properly functioning RO/DI will not leave enough contaminants to feed algae. Spent DI resin will release phosphates and often in massive quantities since they are weakly ionized and will not stick to the resin once its lost or is in the process of losing its electrical charge. Always make sure you change DI when you very first start to see signs of anything other than 0 TDS since its the weakly ionized substances that ge treleased first including nitrates, silicates and phosphates.
By the way have you tested for silicates? Just a thought.

 

[KingRicky]

I have not tested for silicates. I feed Rod's Food, rotifiers, cyclopese and mysis shrimp. I feed once daily, I altenate between the Rod's and the other. I am also dosing PT's Reef Blend daily. I use a filter sock only when I clean the tank and I take it off and clean it immediately after. The only other filtration is the Protien Skimmer and Macro Algea in the fuge.

I am going to break down and purchase a RO/DI unit next week. Hopefully I can eleminate the problem soon.

Thanks for the information.