Phosphates in a Newly Cycled Tank...Where did it come from??

[WhiteCloud]

My 40 Gallon breeder just completed it's cycle with a cocktail shrimp:

Water Parameters are:

Ammonia: 0 ppm
Nitrite: 0 pmm
Nitrate: 10 pmm
pH: 8.2
Specific Gravity: 1.024
Temp: 78 F

I went ahead and tested for Phosphates....just because I had the test available and I was curious.

It came out to be: 0.5ppm

Why? I am using RO/DI water with registers 0 ppm with a TDS meter. I have added nothing to the tank except for the shrimp...which has now dissolved in the tank completly. I have CPR Bak Pak 2R skimmer...which has been getting quite a bit of Skimmate despite no livestock in the tank yet. I am using Instant Ocean Sea Salt...which states it has NO PHOSPHATES!

Any idea where it is coming from??

Thanks

WC

 

[quarryshark]

Could be from the die off during the cycle. Try running a PO4 sponge and see if that fixes you up.
Also test your source water for PO4, I know you ran a TDS test but I would test it anyway.
Also test your salt mix to test their claim.

 

[steve-s]

The shrimp. Tri-polyphosphates are used commercially in the food industry as a means of keeping seafoods crisp and maintainning an appealing color.

Cheers
Steve