Base PPM and Nutes

Something I haven't been able to figure out is...

Lets say PPM of tap water is 200, vs RO water which could be 50...

if wanted my PPM to be 400 for my reservoir, and Im using tap water with a base of 200 already, Then I would only be able to put as much nutrients in to make it 400, right? But if i was using water if a base of 50 PPM, then I would have 150 extra PPM of nutrients?

So does it slow down growth by using water with a high base PPM since you can't add as much nutrients? or does it really not matter...

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Originally Posted by Illusion

Something I haven't been able to figure out is...

Lets say PPM of tap water is 200, vs RO water which could be 50...

if wanted my PPM to be 400 for my reservoir, and Im using tap water with a base of 200 already, Then I would only be able to put as much nutrients in to make it 400, right? But if i was using water if a base of 50 PPM, then I would have 150 extra PPM of nutrients?

So does it slow down growth by using water with a high base PPM since you can't add as much nutrients? or does it really not matter...

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I'm just beginning with hydro myself, and you are asking the same questions I was asking an expert, yesterday ... yes, you are correct on calculating the ppm limit ... whatever is left after your water ppm, is the amount of nutrients you would be able to add... and, if you cant add much nutrient, growth will slow ... plus, the high ppm could be because of bad contaminants ... RO water is very low, mine is 004 ... but, with RO, you also have to add Cal-Mag Plus, and I assume that will add to the ppm, as well ... but, remember I'm very new at this, I haven't even set up my equipment yet, still researching ... :smokin:

Thank you so much for the reply, its the confirmation I needed and makes sense to me

Do you know of a place to purchase RO water in bulk without purchasing a RO system? I can't really afford one

most grocery stores have a machine, where you either refill your own jugs, or buy the empties there ... it used to be 25-cents/gal, but I haven't paid any attention lately ... be sure to check the pH, it is likely acidic ... :smokin:

I've been adding nutes on TOP of my tap water, if I had a tap water with a TDS of 200 and wanted nutes at 400 I would add 400PPM worth of nutes into the res.

If I used RO water with a TDS of 50 I would add 400ppm of nutes

Maybe I've been doing it wrong but thats how i've been doing it and it seems to work great,

but im only on my first grow so dint listen to me too seriously

so always add 400 ppm in that situation?

no don't do that. Image R seems to be right from what I've heard everywhere. I'm struggling with the same issue.

The TOTAL PPM should be what you target. Add your nutes to the res water, then take a PPM measurement of the well mixed solution in your res. In other words your target is your nutes + water = 400 PPM... make sense?

yeah, it is the TOTAL PPM you are looking for, you want to stay in your 'range', and the tapwater ppm must be included in the math :smokin:

Exellent. Thank you!

:thumbsup: