HYDRO-How's Your Math?

Trying to figure something out…If my water has PPM at 320. Mostly limestone ground, so Calcium Carbonate. I want a 1/4 strength nute with PPM around 300. My meter readings initially have ppm at 620. A week goes by… Meter reading now at 400. Is the ratio now 320 ppm water, plus 80 ppm nutes? Or has water ppm lowered also, meaning I would need to add more. Hope I am clear about my question. To me, hydro is just one big, ongoing math equation and this keeps screwing me up.

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Have you been topping off with ph’d water during? if so it’s nutes if not it is a combo of both

topping off 4 1/2 gal solution in 5 gal bucket. To top off, I use pH’d solution with ppm at 620 (320 water, 300 nutes) Takes about 1/2 gal to top it off. I am worried that if I keep ppm at 620, the solution in bucket may end up with double the nutes if the calcium is gone from the water. Probably not a good answer, but I tend to be a perfectionist and it is driving me nuts. @Donaldj, thanks for quick response. Cuz if my water ppm is gone, I may be giving double the nutes.

Here’s why hydro is so nice what you are seeing is your plants using what you give them which is a positive effect since the goal iss to give them exactly what they want when they want it with very little excess. If your ppm were raising it would mean they are getting too much since they are consuming water faster than nutrients odds are the ppm of your water is greatly composed of Cal meaning you shouldn’t have too much of an issue there well water? I would increase the ppm of my nutrients to closer to 400 and see how the ladies respond. The big trick is to check ppm before topping off what you want is the ppm slowly dropping even as water level drops or staying constant this would mean that everything the plant is taking is feeding it if it rises you are adding too much drops sharply not enough etc. Also between res changes you shouldn’t need to add nutrients just ph’d water not to say you can’t if it’s working for you

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So just to be clear , your saying that your water out of the tap starts out at 320 ppm without adding anything… Am I correct?
If that is the case that means you have 320 ppm of something , but there’s no way to tell what those ppm are… Ssoooo I think u need to get a ro system so that way your water starts out at almost or near zero ppm or else I see problems in your future…
I hope I was understanding you right and hopefully I gave u an answer to your question…:slight_smile:


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You don’t always need an RO unit most tap waters have high levels of cal chlorine and minerals that your plant will actually use in moderation if it isn’t broke don’t fix it. The reason I use a RO unit isn’t because my water sucks it’s so that 600 ppm is exactly what I want it to be no variables also means I am able to crank more nutrients into my plants add extra’s and still have a lower ppm also means flushing is easier

I guess my point was that it would be a lot easier to monitor with a starting ppm of almost zero… Somebody else here on the forum said if your water out of the tap is higher than 200 ppm that it might be a good idea to get an ro system… The water that I use starts at 2 ppm and a pH of 5.5 and I’m a nube in hydro and have had great results and I think its because of the good quality water I start out with… Then again who knows I could just be lucky…



Also on a side note I believe I read on this forum that high ppm usually equates to hard water and the problem with hard water is that the minerals that are in the water aren’t chelated , so that means that even though they’re in the water the plant can’t absorb them like you are saying , now if that’s true or not who knows I’m just basing this off of all the information I’ve read…


@Donaldj,@peachfuzz. An RO filter would solve my math issue. I had tried to find one I could adapt to fit onto my hose. Am closet-growing deep in the heart of Texas in less than Ideal conditions. But my learning curve is slowly getting straighter thanks to y’all. lol

@peachfuzz Well, the decision has been made… I will just subtract water’s PPM throughout entire grow for my nute strength calculations. At least this will end any guessing and satisfies my desire for a concrete number to work with. To all who have responded to my numerous questions, a Big Thank You. I have gone from total root rot to a large, healthy root system, gnats, low oxygen in too hot water, leaf spots, learned the basics of ph and nute adjustments. I spent 3 months studying literature on hydroponics, but having yall to bounce stuff off has been way more beneficial. Just switched to 12/12, waiting on 2 new mars hydro 600 watt . @FloridaSon- thanks for the like.

I rarely factor my tap water ppm and though I own RO unit I still use rain water or tap water most of the time however I make my own feeding charts which means my ppm is lower than reccomended. Less is more so long as it’s available once you start being rigid to feed doses on bottles you start getting lockouts and build ups

No problem, Brother!

It’s an interesting topic for me as well. I do soil outside, but am extremely interested in this!

I miss out on too much grow time during the Winter. My wife is pushing me to get set up for indoor. Not that I mind that kind of push! :wink:

I would like to try a hydro system, but everything involved seems so daunting to me! Really not much room for error. Once I get good with soil indoor, I will attempt hydro.

In the meantime, I try to read up and learn. Experience is my best teacher, but I’m not willing to invest the funds needed until I can get a grow space set up and dialed in.

I’ll be watching…


One thing I can say for sure is once you get the hydro bug you will think of soil growing way different all the variables in soil it’s almost more complicated when you know exactly what your plant is getting and can tweak things without waiting for soil to dry or rinsing it. Growth rates are faster flushes a breeze shy of a faulty pump or meter it’s pretty hard to screw up

Yeah, you forget that Murphy guy stalks me everywhere I go!!

I’m confident that once I am able, y’all will lead me to success.


it’s called redundancy I own 3 pumps have both meters and test strips extra air lines and stones have 48 hours roughly if a pump breaks aside from that very few things will kill your ladies without showing signs first

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@FloridaSon. If I can make progress, there is hope for anyone! I’ve come a long way since I saw my buddy’s grodan block grow in his closet. Went and got some blocks, seeds and off I went. Once they started to grow, I decided if full strength nutes were good, then double that must be better. lol. If you want to start, just get 1 bucket, cheap light( I used a 100 watt LED bulb with a 12 inch reflector from Walmart). Once you have some small, positive results, you WILL be hooked.

That’s another reason for the delay. The funds aren’t available to get what I need to get set up. Some people live week to week. Some of us struggle to get to the end of the week.

My wife is pushing, so since we don’t have the materials needed for home remodeling until tax return, I’m turning these floor joists into a frame for a grow…

The good ones I’ve already taken ended up becoming my kitchen sink counter frame.

Sorry…going way off topic!


I have no doubt about getting there with all the access I have to great help.plans are also in the works for me to get to the Lab. :heart_eyes:

I’m sure I’ll be hooked! I’m in love with the density and node spacing that can be achieved. It’s the main reason I would like to get my feet wet. Yes, pun intended. Damn you Piers Anthony!! LMAO

I’ll never forsake outdoor grows though. Hell, I live in the Sunshine State! :wink:

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@FloridaSon I started with no knowledge, a 20 dollar 100 watt LED daylight bulb with reflector(Total 20 bucks). Aquarium pump 9 bucks, airstone 1 buck. Old Tidy Cat Litter container with hole in top for net pot(cat donation).


@FloridaSon,we do what we can with what we have, I’ve seen some very good set ups out of what is laying around, side note bloody eye in the sky is way to low over my place for my liking.ATM

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