Reverse osmosis setup advice/recommendation

[LordHumungus187]

So I’m not new to growing, and in general, I have a pretty green thumb. I also like to think I’m good at reading my plants and doing what needs to be done to correct the issues but I’m noticing that most of my grows go a little funky when it comes time for flower. My stuff is always super strong with great terpenes and great euphoria, but I have never gotten the full potential of a grow. To give some background, I usually grow clones outdoor and auto flower in a tent inside. I primarily have an AC Infinity set up for my tent and feel like everything is dialed in. I’m starting to think that my water is my main problem because it is the only thing that I don’t have ultimate control over. I have well water and it is definitely alkaline usually somewhere around 7.8 …obviously I am constantly trying to lower my alkalinity to get it to neutral or slightly acidic, and I believe that the salts building up over time are affecting my soil’s pH and nutrient absorption. I have been thinking that I may be in need of a reverse osmosis system. I only need to water four plants at a time so I do not need a high output system. I want something that is as simple as possible, and don’t want to have a giant holding tank in my house. I probably only need 2 to 3 gallons worth of water every two days. Who has experience with RO systems? I’m looking for recommendations for a simple/least invasive setup that I can depend on so that I can remove the unpredictability of my water and I don’t have to constantly fight it to get it within the parameters it needs to be for my grows. Also help me understand.. I hear about waste water and the ratio of waste water to clean water. What happens to the waste water? Most systems that I see have three filters and a holding tank. Is the holding tank for waste water or filtered water? Does it also need to have a drain for waste water? As always, I appreciate the advice.

 

[compostmike]

The 7.8 pH isn’t really the scary part by itself, it’s the alkalinity behind it. If that well water is carrying a bunch of bicarbonates/carbonates, you can pH it down all day and the soil still slowly gets pushed upward over time. That shows up a lot right when flower gets hungry and the root zone needs to stay active.

For 4 plants I wouldn’t overbuild it. A small 50-100 gpd under-sink RO or portable “RO Buddie” type unit would make plenty. The holding tank is for the clean RO water, not the waste water. Waste water/brine goes out a drain line, usually into a sink drain, washer drain, or a bucket if you want to reuse it outside. Ratio depends on pressure and unit quality, but cheap systems can waste 3-4 gallons for every 1 gallon clean, better ones closer to 1:1 or 2:1.

With well water I’d definitely run sediment prefilter first, and if you have iron/sulfur issues that matters too because it’ll chew up membranes. Also check your water with an EC/ppm meter and if possible an alkalinity/KH test. That’ll tell you if RO is actually needed or if a partial blend would solve it.

I’d probably use RO blended back with a little well water or re-mineralized lightly rather than straight dead water every time, especially in soil. The microbes and exchange sites still want calcium, magnesium, and trace minerals. Something like 75% RO / 25% well water might tame the bicarbonates without stripping everything flat. Then watch runoff/slurry pH over a few weeks instead of chasing every watering.