Deionized Water Usage?


Can deionized water be used in the Grobo? My water company sells it as an alternative to distilled water.


Hey BoldSolar,

Great question!

You sure can. Basically the same as Distilled or Reverse Osmosis, water without the ions.
Distilled, RO, de-mineralized all remove cation and anions.

Grobo will sense the low EC and add a Calcium/Magnesium buffer.

I still have some rainwater from Halloween and some melted snow from Christmas I want to test, both should be fine in a Grobo as well! :wink:



I plan on using a zerowater filter which eliminates all minerals (Total dissolved solids 0 ) rather than distilled or RO water…but zerowater doesn’t change the pH of the tap water. (in Portland Maine the latest reading at the plant after treatment but.before distribution.was 8.3) … I guess you recommend distilled or RO because of the low pH and the lack of minerals. The zerowater will still have a higher pH than recommended for hydroponics which i believe is 5.8 with the distilled and RO water being a lot closer to the 5.8. I believe I read that pure rain water was about 5.8 also. Distilled water is 7.0 immediately after distillation but quickly changes to a lower pH because of CO2 absorbtion…Is my understanding correct? It may be less expensive for me to buy Grobos extra “nutrient bottles” to change the waters pH rather than buying distilled water and having a lot of empty plastic jugs… Thanks in advance for a reply…


Hi Kirk,

Your Zero water filter will work very nicely and might even save you some money in the long run. I recommend Distilled or RO because of the lack of pre existing solids. Just like Bruce Lee would prefer to teach his art to a student that had never been exposed to Karate or Judo, (They pick up bad habits that need correcting in his opinion) I prefer to start with a blank water ‘slate’. I then add what I want, not having to worry about extra minerals my plants cannot use. (Fluoride anyone?) The system automatically adjusts the pH, so the starting point doesn’t matter.



Excellent I already have one in my cabinet. I know what I’m switching to lol.


Can I use this? I bought it for the storage really. I have a zerowater pitcher I plan on filling this jug up. Be a shame to throw 5 gallons out though.


Yes absolutely, it says on the cap purified by reverse osmosis (ro). Reverse osmosis is exactly what you want as it takes out heavy metals and minerals, creating a blank slate to then allow the grower to add what is actually needed. Use it worry free!! You


That’s what I thought just wanted to double check.


It does say minerals added, but I wouldn’t worry about that.



Everything sounds great until this part “minerals added for great taste” I’m sure there’s not enough in there to impact the growth. The great taste minerals are not one the plants seek out so why add another possible blip on your plants health outcome?

The fact I only have the one dedicated plant growing at a time I personally would go the extra distance and get strictly RO or distilled water. The water pictured is clearly made for human consumption. Would it hurt the plant, maybe not. Will it help it?..nope.

Just my 2 cents.

Edit: I missed this first time around:

Stick with the Zero filter, plants will be happy with a blank slate.


Yeah I just didn’t wanna dump 5 gallons out if I didn’t have to was all lol. The zerowater filter is definitely a slow fill process.


For sure, it’s a legit question.

Yeah I wouldn’t have the patience to do the ZERO filter water and completely understand not wanting to waste the jug of water.


How the world you get it to put yalls usernames when responding btw. Making it look like I’m ignoring yall lol.


If you want to tag someone put @Bongsmoker89 (@their username) :+1:


@stephen this might be a dumb question. Can you use regular bottle/filtered water? I check the EC and it read 0 plus the PH is about 7.5-8. Would this be similar to distilled water/ RO water which also has EC of 0


Hey @Jamminbear, I’ll throw my two cents in here. It’s always better to use ro water as it is a relatively clean slate. If you use filtered water with a high ph, you will end up using your ph nutes to bring the ph lower, thus running out of ph solution quicker than the other nutes. Hope that helps.


Hi Jamminbear,

As @rouleauj mentioned, I prefer RO or distilled as they allow us to start from a clean slate, adding only what we want and nothing we don’t. (Think fluoride in some drinking water for healthy teeth) If your water has an EC of 0, your system will buffer with Cal/Mag and keep your pH balanced.