Nitrates, and ORP question

[DiverDavid]

I have had my aquarium up and running since February. I have had fairly stable parameters, the following are from yesterday.

Cal 385 (increased my dosing last night has been around 450)
Alk 8.7
NO3 -64 ppm (Red Sea)
PO4 - .56 ppm (Hanna)
Salinity 1.025-1.026
Aquarium is 180 gallons with sump.

I started Vodka dosing about a month ago, up to 2.7 ml daily. I don't seem to be seeing any change in my Nitrates, my phosphates will come down slightly with a fresh change in GFO. I am also running carbon.

My question is this when should I start seeing the NO3, and PO4 start dropping? Also I did a 20 gallon water change yesterday and the ORP on my APEX went up yet again (value 475) ORP stayed steady until about 2 months ago then started rising. It seems overtime I do a water change ORP goes up. I'm tempted to turn it off and stop looking at it.

My main concern is the NO3 and PO4, skimate is almost black. I do not have a bunch of algae everything looks pretty good although I have lost a couple of small SPS frags. Should I be expecting to see the nitrates and phosphate dropping by now?

Thanks!

 

[Randy Holmes-Farley Verified Community Expert]

An ORP probe needed cleaning often results in an observed rise in ORP.

It might just take more vodka to offset the additions of N and P from foods. Nitrate will drop more, phosphate not so much.

 

[DiverDavid]

What is the best way to clean the ORP probe?

 

[pdxmonkeyboy]

A simple sponge will do.

 

[Randy Holmes-Farley Verified Community Expert]

yes, gentle wiping is usually sufficient unless it has calcium carbonate deposits on it, in which case soaking in acid will do the trick.