PH and Nitrate Levels

[NCFord]

What is the target PH and Nitrate levels for open boilers? As a general rule. I have to service an open boiler that we do not know the history of. I got the test kit and boiler treatment from Alternative heating and supply and plan on just draining the system and adding the boiler treatment per their instructions. I would like to test the PH and Nitrate level in the current water but don't really know what levels it should be. I know the PH should be high, but what number. The test kit they provide does not provide any guidelines, just instructions on how to get a value.
I am very used to closed systems but not so much open systems.

 

[Sawyer]

Attachment shows levels that were satisfactory, I am not sure of the upper and lower limits. Hope this helps.

 

[mustash29]

This is for an Empyre Elite 100/200 indoor gasser.

Draw a water sample once a year and forward to your dealer for testing.

Water properly treated with Pro-Fab approved water treatment should have a ph level between 8.8 and 11.0, a nitrate level between 730 and 1460 ppms as NaN02, and a conductivity must be less than or equal to 4000 mmhos.
If the pH is not within tolerance, treat by adding a ratio of 1 part of Pro-Fab approved Wood Burning Furnace Treatment (WBFT) to 300 parts of system water and retest. If the nitrate is less than 730 ppm, treat by adding a ratio of 1 part WBFT to 300 parts of system water and retest. If the conductivity is higher than 4000 micromhos, drain 50% of the system
water. Refill and treat by adding a ratio of 1 part WBFT to 300 parts of system water and retest.

 

[NCFord]

Thanks