GFO and numbers

[drakebuffie]

Just recently got several hanna checkers. Tank has been up for almost a year. Lost a few fish in the beginning but none in a long time.

Recently lost 2 Zoas and my hammer quit opening. After testing with hanna I found my trates were zero. My phosphate checker came in a week later and first phosphate check was off the charts.

Yesterdays test right after a 6 gal water change in a 65 gal tank my trates were .7 but phosphates were .65. I had doubled my feeding in order to get the trates up so they are headed in the right direction but I would like to get the phosphates down. Is running gfo in my filter socks or a bag near the return pump the right way to do this? I am thinking my zoas and hammer died due to trates being near zero for a long period of time but I dont understand why my candy cane, montis and other leathers did so well as well as another zoa that is spreading nicely. Might never figure that out and just need to get trates higher and po4 lower.

I use rodi water and change my media when the tds meter gets above 003. Was told by a guy with beautiful tanks he will go as high as 5 before changing his rodi media but I will keep it as low as possible. my well water is in the 100s before rodi so 003 is acceptable to me.

 

[DanyL]

There are quite a few things going on here.

First, stop overfeeding, you are fueling the tank and it's not a good way to raise your nitrate but will raise your phosphates quite a bit as you already noticed.

A GFO is a solid option to decrease the amount of PO4 in the water, I would use it in a bag if no reactor is available.
Dosing nitrates would also help you to decrease PO4 levels by consumption as well as to raise NO3 levels as the same time.

As for your RODI, it doesn't really matter how much you start with (I'm at 680 TDS for comparison), but it does matter how much you end up getting at the output. The recommendation for TDS 0 is to make sure there are no harmful elements dissolved within the water, 3 TDS or 100 TDS both may contain aluminum, tin and other harmful elements, so unless you wish to take the chance of contaminating your tank and look for unknown reasons your tank is experiencing issues I would target a solid 0. It also sounds like you aren't using resin at all (100 to 3, which makes it an RO unit, without the DI), so it isn't even a big deal as you might think it is (for me, due to the high TDS I start with, it is), just add another stage and be done with it.