How Much Po4 Actually?

Tank size, solution size, and grams added are missing for someone to check this for you.

 

I tested on Zorfox calculator and these numbers seem correct.

 

What is you pH and type of Fe being dosed.
You may be losing it with the Fe.

 

Hey fitos I’m actually been having this same exact issue with dosing my KH2PO4 this week. After dosing 1.5ppm of po4 3x a week my test always show up at 0.3-0.5ppm I figured it was consumption, so I wanted to dose a little more to get to 1.5ppm a 10:1 KNO3 to po4, so I raised my dose to 15ml instead of 10ml, my ferts calculator said I would be dosing 2.25ppm that’s .75ppm more of po4 I dosed 3 times this week tested my po4 just this morning it was showing 0ppm-0.25ppm? I’m starting to think it’s my test kit, if you find anything out let me know and I will do the same thanks! My ph is also 6.4 and I dose CSM+B chelated for micros 0.3ppm every other day does this have anything to do with it?

 

So your dosing .843ppm of PO4 3x a week and at the end of the week you end up with .3ppm of po4 so your plants are possibly consuming .54ppm of each dose, I wouldn’t think this is completely out of the ball park, all considering multiple unknown variables it very much could be contributed to just rapid root growth, PO4 is contributed to many key functions of photosynthesis and it could just be contributed to plant growth. My tests show an uptake of almost 1ppm in a day, but also I’m not an expert this is just from my experiences lately with dosing Po4. I feel like my tank likes and uptakes more po4 in comparison to other nutrients, but I also have a lot of new plants expanding their root masses and all of that good stuff. As far as fe goes I really can’t contribute because I don’t have a good test kit yet for fe. I hope this might help. T.Smith

 

Seems like there might be K in maybe something else you dose? I use reKHarb for kh and it adds about 10ppm of potassium each dose. Maybe the test is just showing more then is actually has? Your JBL test kit, is it the master kit with the liquid test? or is it the dip strip? I know jbl makes a test kit that uses your phone camera to read the colors and they are really inaccurate because all cameras pick up color differently.

 

Oh awesome I’ve been eyeing that test kit up for a little while glad it’s been working alright for you. Maybe adding the Fe/micros does have an effect to the po4 but I always thought the reaction between po4 and iron you would loose the iron not the po4. I did my po4 test today, Sunday I did wc added back the po4 mid day, tested for about 2ppm right after, added micros this morning and po4 tested in the evening at .25ppm, so my test show my plants used 1.75ppm in 24hrs? Do you think this is accurate, I’m useing cheap api test kit for the time being not sure how accurate it is?

 

Okay cool appreciate it!

 

@fitos100 have you calibrated or validated your PO4 test? Toss a day’s dose in a cup of ro water and test it. If it doesn’t go off scale it’s not detecting the inorganic form, and is only showing the organic. Had this with a nitrate test and had to switch brands. Don’t know if it was just a bad bottle, or the test design.