Phosphate after RO/DI

I also saw this from our resident water expert (AZDesertRat) on another thread.


"0 TDS does not necessarily mean 0 phosphates. Phosphates like silicates and forms of ammonia are weakly ionized and may not register on a hobbyist grade TDS meter, it would require a conductivity or resistivity meter to get to that level for sure.
That being said, if you are getting a reading of 0 TDS I would say its safe to assume the phosphate levels are low enough to not be a concern in the RO/DI water."

 

Okay just made a batch of fresh salt water for a water change. 0 TDS, Instant ocean salt, 1.025 on the refractometer and getting a .03 phosphate reading on the Hanna Checker. What do I do to bring that to zero. A little baggie of GFO for 24 hours? If so, how much? Any help?

 

What salt do you use? I had a problem with a batch of Reef Crystals, and a similar problem with Red Sea Coral Pro. Bad batches I guess. I ran a BRS reactor from my newly mixed salt through GFO for a day, and then did my water changes. 0.00 after on Hanna.

 

All salt mixes have some PO4. 0.03 is rather typical. It's not of much concern if you have a method of control for PO4 in your system.

 

My last bad batch (RSCP) would read between .15 and .09 over 3 mixes of 25 gallons. I have plenty of control methods in place in my system, but I also feed heavily, so adding .15ppm (15% total water volume changed) wasn't helping. :-/

 

Well sure; that's rather higher.

I should clarify: anything under 0.05 I wouldn't worry about.

 

I do run GFO in a Phospban reactor. I have just been battling this algae forever and am trying my best to eliminate it for good. I want to make sure I am adding no extra phosphates to my tank anywhere.

 

kalkwasser is supposed to precipitate out the phosphate and many other ions like metals etc. in RODI. Maybe run a very small amount of kalk in your top off water.

 

I run a calcium reactor, would the kalkwasser interfere with that? When you say small amount you mean like a teaspoon a gallon?