Minor nutrient mystery

Detritus Mulm

Guru Class Expert
Jun 12, 2005
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I was checking my KH last week with one of those all-in-one strips as I did not believe the readings from my main kit. The KH test was OK, but I noticed a touch of Nitrites. I thought this was strange, since Ammonia was 0 and Nitrates around 10 PPM. I was told elsewhere that low Phophate can interfere with the nitrobacter.

So I tested my Phosphate with my crappy kit and it was the standard piss green/yellow colour, which should be somewhere between .2 and .5 BWTFK. I decided to add about 1 ppm of Phosphate two nights ago and it was back to the standard colour when I tested last night. Although plants seem to have had a busy day. I added another 1 PPM last night and the colour had fallen off again by tonight. The plants don't seem to have grown as much, but there are a ton of leaflets tonight.

As you can probably tell, I'm a Heretic (No EI Yet), so I don't add any NO3 currently, but check it weekly to make sure it's OK. although I do add traces, K and Mg. I would have expected my Nitrates to drop off the charts with all that Phophate being used up. But it's still around it's usual 10 PPM, what's up with that? I did add some Pond tabs to a couple of pots a few weeks ago, but I would have thought the effect would have worn off by now?
 

Tom Barr

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Jan 23, 2005
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Re: Minor nutrient mystery

Detritus Mulm said:
The plants don't seem to have grown as much, but there are a ton of leaflets tonight.

As you can probably tell, I'm a Heretic (No EI Yet), so I don't add any NO3 currently, but check it weekly to make sure it's OK. although I do add traces, K and Mg. I would have expected my Nitrates to drop off the charts with all that Phophate being used up. But it's still around it's usual 10 PPM, what's up with that? I did add some Pond tabs to a couple of pots a few weeks ago, but I would have thought the effect would have worn off by now?

Well if you do rely so heavily on the NO3 test kit reading, have you done a calibration or do you use a high quality test kit(Lamott etc)?

Also, what harm would it do to try out adding NO3 by adding another 10-15ppm ?

A simple water change would knock it back down........
The opther issue, I'm not sure if you add K2SO4, but you should if you do not add KNO3.......

You can work through this easy enough without going EI.
But the amount of work, might not be worth it for you, if so, then you should try to calibrate the kit. Make a 20ppm reference, then a 10ppm, a 5ppm and a 1ppm.

Make the 20 first then dilute from there with DI water.

Regards,
Tom Barr
 

Detritus Mulm

Guru Class Expert
Jun 12, 2005
147
0
16
Re: Minor nutrient mystery

Tom Barr said:
A simple water change would knock it back down........
The opther issue, I'm not sure if you add K2SO4, but you should if you do not add KNO3.......

You can work through this easy enough without going EI.
But the amount of work, might not be worth it for you, if so, then you should try to calibrate the kit. Make a 20ppm reference, then a 10ppm, a 5ppm and a 1ppm.

Make the 20 first then dilute from there with DI water.

Regards,
Tom Barr

Thanks Tom,

I do add KH2P04 occasionally, but this will be done weekly (or more) from now on. It was obviously the limiting factor for the plant growth.

Thanks for the tip about calibrating the N03 kit.

The BBA has taken off since upping the P04, so I've upped the CO2 for now.