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Cheapest PH stable water best for coco r/o vs dispensed water

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One problem I have had with coco is keeping the ph in the coco stable. When ever I used store bought water, it was super easy to keep the PH stable because the water's PH is stable and my nute's PH is stable; however, that water is expensive.

But, I found a solution.

R/O vs dispensed water.

Dispensed water is the water you can buy at the automated machines. You can usually fill up the 5 gallon containers there. The cheapest one I found is $1.50 for 5 gallons.

That might sound expensive, but it's not, compared to the alternatives.

Dispensed water remains stable, meaning that if the PH is 6.7, and if you leave it in the open or a bucket with an air stone in it, 24 hours later, the PH will still be 6.7. This is ideal as it makes keeping the PH in coco stable much easier. Also it is way better for DWC and such.

You might think it is cheaper to run and r/o system, which I recently purchased, but it's not. First, if you have to pay a water bill, don't even consider an r/o system because waste more water than it produces. You have to tap a waste line into your pluming. You have to pay for all those gallons of water the r/o filter waste. This ends up costing you way more than if you just bought 5 gallons at $1.50-$1.90.

Even if you have well water like I do, the r/o system can still cost you more, depending on how many gallons of water you feed your plants a year. Keep in mind, every six months you are supposed to change the membrane and the filters to your r/o system. However, even if you only change them once a year, they still cost about $144 for all of them.

If you use 60 gallons of water a month, thus 720 gallons a month, you are paying 20 cents a gallon. That is if the filters last you a year.

Dispensed water per five gallones at $1.50 cost your 30 cents a gallon, and at my Walmart, the slightly better dispensed water cost .37 cents a gallon. r.o water will cost .40 cents a gallon if you end up having to replace the filters ever 6 months as needed.

Now that is if you don't have to pay a water bill. I you have a pay a water bill, my god, the r/o system is going to cost you so much per gallon of water that you are WAY better off buying dispensed water.

I have tried three locally dispensed water types, and so far, all have stable PH when in the open air, even with nutes in them. This means, the only thing in DWC that would change your PH would be your plants drinking too much or too little nutes, or root issues. Same with coco.

What about distilled water?
A distiller, heats up the water, causing evaporation, then condenses and cools the evaporated mist into water, and releases it into a container. The end result is my well water going from 150ppm to 11ppm, and a stable low ph of 5.1

With distilled water I must use ph up.

the cost per gallon however still is somewhat high because water distillers take about 5 hours to produce one gallon of water. The cost of a water distiller that produces 1 gallons at a time is $200. That is what I have. The cost of one that produces and can store 5 to 30 gallons is $500-2000.

The cost of electricity per gallon if it takes 5 hours to produce, which most all do, cost .27 cents a gallon, and that is if you are lucky enough to have a 9 cents per watt cost. Lots of stats have a .12 cents per watt cost, which brings the gallon to .36 cents per gallon. Also consider the big cost of the unit, which effects the cost per gallons for a few years.

So far, I haven't found well water or tap water that is PH stable. It slowly rises in the open air. I have tested two wells and two cities tap water.

I have tried different filters, even 5 stage filters, and they do not make the water PH stable. They do make the water PH rise slower, but not stable.

I haven't tried the zerowater filter yet because the cost per gallon would end up more than what I can get from a water dispenser. about .46 per gallon.

The point of all this? Think before buying an expensive r/o system or distiller.

Perfect Sun LED

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I want to clarify. It depends how many gallons your r/o actually produces for you a day determines how much it will cost you per gallon. They base the six month changing of the filters and membrane on how much the average house hold uses, which is probably less than 60 gallons. I based on the cost on 60 gallons processed a month by the r/o filter.

Perfect Sun LED

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I've had my dispensed water in an open bucket with an air stone in it for two days. Ph has remained 6.3

I haven't had to adjust PH at all. I never could do that with well water or tap water.

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I found a work around for my low pressure not filling up the tank past about half a gallon in my r/o system. I place a 5 gallon water container under the r/o spout in my sink and just leave it on to drip. It fills up in about 12-15 hours. This makes it easy to get at least 5 gallons a day.


New Member
I have used R/O for years , build yer own rig cheaper , use 75 gallon a day membranes use 2 of them & one set of filters , set the waste water to barley trickle & the R/O side is producing more water than the waste , let it run into a 5 gal bucket when full open up the watse side water vales & let it flow 10 minutes to flush the membranes
use pin needle valves to adjust the water flow to a fine adjustment
what your doing is forcing the water thru the membrane at a high rate but as long as you flash the membranes they will last over a year of more , I flush the mems before & after every R/O run , I'm on 2 years on these 2 each 75 gal / day 3M mems right now
still show less than 10PPM this morning
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