[JohnsTank]

I have been using the PPS method of dosing ferts for a month or so. I have been testing PO4 and am continually coming up zero on my API test. I only have 8 clippings planted in a 45g so not sure what the problem is but I've decided to dose my KH2PO4 in its own solution in addition to my regular regime. I just don't know how much to measure out and mix nor do I know how much RO to use.

 

[Darkblade48]

First, have you tested and calibrated your test kit to ensure it is working? I noticed that you were having troubles with fluctuating nitrate levels in your other thread as well, so a test calibration would be the first thing to do.

 

[JohnsTank]

First, have you tested and calibrated your test kit to ensure it is working? I noticed that you were having troubles with fluctuating nitrate levels in your other thread as well, so a test calibration would be the first thing to do.

Excellent point. I considered doing it last night but I felt that being a new API kit with what I thought was a clearly depicted color chart, it wasn't necessary. In any case, I'll do it tonight. Thanks for the reply.

First, have you tested and calibrated your test kit to ensure it is working? I noticed that you were having troubles with fluctuating nitrate levels in your other thread as well, so a test calibration would be the first thing to do.

I was looking for a site to show how to do this. I found it last night but can't find it now. Do you know of any resources?

 

[John Wong]

This is just my own way, not sure whether it is correct or not.
Ppm used is based on
K 39
P 31
O16
H 1
KH2PO4 136
PO4. 95
250g / 1000ml of water at 25 degree Celsius.
250 *95/136=174.6g/litre
0.1746g/ml

Your tank is 170100 ml

0.1746/170100*1000000=1.0265ppm by weight.

In other word, 1 ml of saturated kh2po4 will raise your tank phosphate level of 1ppm




Sent from my MX4 using Tapatalk

 

[Darkblade48]

I was looking for a site to show how to do this. I found it last night but can't find it now. Do you know of any resources?

Have you checked the sticky?

 

[JohnsTank]

Wow, what a great sticky. I wish I had found it before I found the chemist method. Measuring grams and a lot of mixing. Only finished the Nitrate calibration last night. It was close but the API 20 ppm nitrates was quite different. On the card the 10 and the 20 look nearly identical but the 20 in reality looks much more orange. Very good to know.

Will do the PO4 tonight.