What happens to runoff EC ratios?

[phxazcraig]

Using DTW autofeeding 7x daily in coco/perlite mix.

Late in flower stage now.

My EC is consistently higher in runoff than input, sometimes over 200 points if I don't water 'a lot'. A couple of times I've dumped 4 gallons of runoff back into my 30 gallon reservoir along with a bit of RO to lower the EC where I want it.

M question has to do with the quality of the runoff EC - is it likely to be in the same ratio as the input EC? Or would I expect it to be disproportionately lower on something like calcium or magnesium, or the nitrogen got sucked out more (or less) than the potassium, etc? I put a LOT of runoff into my houseplants and yard these days, and I would be very handy to once a week just be able to re-use a 5-gallon bucket full of runoff into a half-empty reservoir.

 

[growsince79]

Using DTW autofeeding 7x daily in coco/perlite mix.

Late in flower stage now.

My EC is consistently higher in runoff than input, sometimes over 200 points if I don't water 'a lot'. A couple of times I've dumped 4 gallons of runoff back into my 30 gallon reservoir along with a bit of RO to lower the EC where I want it.

M question has to do with the quality of the runoff EC - is it likely to be in the same ratio as the input EC? Or would I expect it to be disproportionately lower on something like calcium or magnesium, or the nitrogen got sucked out more (or less) than the potassium, etc? I put a LOT of runoff into my houseplants and yard these days, and I would be very handy to once a week just be able to re-use a 5-gallon bucket full of runoff into a half-empty reservoir.

People use recirculating systems all the time. You just need to change the water every week.

 

[N1ghtL1ght]

M question has to do with the quality of the runoff EC - is it likely to be in the same ratio as the input EC?

most likely not.

but next to impossible to say whether an- or kations are more missing.

fresh solution gives you the only guarantee.
nute ions aren't absorbed at equal speeds, so even the frequency of fertigation will change some of the nute profil the plant feeds