Nitrates in Top Off Water

[dwsindy]

I am using DI water for top off's and water changes and have been fighting a nitrate problem. Today I checked the water from my DI and measured 2ppm of Nitrate. I don't believe I should be reading any Nitrates. Is my assumption correct? I have new filters ordered for the RO/DI unit and they should be here Monday. I am using Salifert test kits btw. Here is all of my parameters measured today:

no3= 10
n02= 0
nh3= 0
cal= 390
kh/alk= 3.43
ph= 8.1
sg= 1.0265
temp= 78.6
mg= 1125
po4= 0

[O'Man]

You might want to test your water before the RO/DI unit to see how effective it really is.

[dwsindy]

Good point. I will check nitrates from tap now. but I do know the RO/Di is working as my TDS is 0 out of DI and around 3 or 4 out of RO. I have had this unit for a year now.

[drummereef]

Sounds like you are getting the replacement media just in time. :) Do you test the tds of the RO/DI water? I would test both the RO stage and the DI stage seperately.

[dwsindy]

I just thought I should update on the nitrates. I received my replacement filters yesterday. I hooked them up and flushed a couple of gallons of DI water and then checked the nitrates and they are now 0. Time for a water change now!!