I had him test the phosphate twice. Same result. I wonder if the previous two people even tested for it? They just left that space blank on their sheet. I assumed they had tested and it was okay. Maybe they saw the tank was cycled, knew I was using RO
water, knew I didn't have anything it there, knew I wasn't feeding anything to the tank, so didn't test for it because it should not have been there. Hmmmm....could be.
I got cured live rock from LFS
. Cycled with that.
I would be surprised if it was the RO
water. That would have to be pretty bad for the store to be selling. But, you never know. That is why I am going to have it tested again. I did start the tank with tap water, but have since done several water changes with RO
. I did have them test my tap water but don't have the sheet for it any more. Since I decided to switch to RO
I didn't keep it.
I just looked at my tank and thought of something. For my substrate I used play sand that had been in my freshwater tank before this. This sand did cause the tank to start to cycle before the live rock went in, but once it cycled I figured everything is okay to go ahead. But, I wonder if the old sand could be the source of my phosphates and the first two times they looked at my water they didn't test for phosphates? Before I used the sand for my fresh tank I would have rinsed it many many many times before using it in the tank. The fresh tank had been running for a year or so, maybe more, before I decided to switch things up and make it a salt tank.
I always had good water in the fresh tank, but I don't know if they test for phosphates when they test fresh water. When I first had my salt tank tested I also took in the water from my two fresh tanks. They both had 0 ammonia, 0 nitrite, and only traces of nitrate, and they were due for my regular weekly water change the next day. Neither of those tanks has sand substrate.
What do you think? Could the sand substrate account for a 1 phosphate reading? Believe me when I say I probably rinsed it in a bucket 15-20 times and made sure the water was clear before using it. That would have been over a year ago.