I live in Hawaii. The tap water here is considered excellent, but that really means not a lot of calcium and magnesium. But there are other solids in the water, I think mostly sodium. I don’t think the EPA requires the water companies to monitor that.
The reason I say this is that with an EC meter (Apera GS2, if it matters), the tap water at my house is 0.92, which I think translates into about 500 ppm. But sodium is a solid that affects the EC meter. What I think is happening is that we have more salt in our water source than is common. When you dissolve it in water it separates and the chlorine evaporates. The county water reports say we are low in chlorine and other EPA-monitored elements, but I see a somewhat high EC. I think it’s sodium.
Using RO water would raise my costs substantially, so I’d rather not. How harmful will it be if I allow the ppm of my nutrient solution to go higher than normal, if a lot of the mineral content is sodium? Is this a big enough issue that I should splurge on a more elaborate water test?
I don’t think further testing is necessary if you’ve already isolated the problem.
I wouldn’t worry about it unless you see sodium toxicity symptoms (which will present as deficiencies.) Sodium is a salt that will submarine your grow media pH and may inhibit nutrient uptake. If you have a hard time managing runoff pH, then switch to RO water to eliminate the sodium.
Not sure I’m understanding completely. I do monitor and adjust the PH both of my mix and nutrient solutions, so if the sodium is throwing the PH off then I have offset that using PhDown. If the only impact on plant growth is the effect on the PH, then I shouldn’t have a problem. If the sodium itself is toxic then I do have a problem.
All salts are additive. You must account for this in your tds. You cannot add 900 ppm of nutes to your mix as the total will be too high for the plants.
An R/O Buddie is under $100 and will process 50 gallons per day. Frankly, that is not very expensive.
That looks like the ticket, and was new to me. The RO filters I saw were to put in line with a sink and were far more expensive. RO Buddie seems to be designed for aquariums but would be good enough for me. I’m not going to drink it anyway.
I think I need some tubes and adapters. I generally mix in 5 gallon water bottles and need some way to fill multiple bottles without being present. Looks like it would take a couple hours to fill one bottle, so I don’t want to have to stand around waiting for it. I can probably cobble something together from sprinkler supplies at Home Depot.
I went to my local car wash and got a 30 gallon detergent barrel for free. Washed thoroughly and would water plants from that. @Not2SureYet has it now.
The RO buddie fills up a gallon in about 20 minutes. Not sure what your water prices are but keep in mind that there will be about 4 gallons of waste water to 1 gallon of clean water.
That makes sense. 20 minutes per gallon means 1:40 for a five gallon bottle. I’ll try to figure out a way to daisy chain them so I can fill several bottles without paying attention to it. I would do this outside so I’ll just let the waste go to the ground. The peace of mind about all the sodium seems to justify the wasted water for me.
It seems like the waste water isn’t all that bad. I can water the lawn with it.
Not all that high. If I get 4 gallons of waste for 1 gallon of purified water, that means the waste should be about 20% higher than straight out of the faucet. A bit less since some of the solids will stay in the filter. Good enough for most plants, I think.
We have them as well but make sure to still test the TDS. They’re not always the best at keeping up with filter changes. I’ve seen some as high as 125ppm.
I haven’t really looked for these. I do know Walmart sells RO water for about $2/gallon. It seems like that would be too much of a pain for me even at $.25/gallon. I’d be going out for water too often.
I ordered the RO Buddie. For me, the key insight is that there are RO filters designed for aquariums that are way cheaper than the ones permanently installed in the house. I’m going to give that a try.
Once I knew about the aquarium aspect, I found this:
That would probably be perfect for me. Much less waste, faster, and with a pump to stabilize the water pressure. I couldn’t find a vendor willing to ship it to Hawaii, though, so for now I’m going to try the RO Buddie. If that makes a significant difference in my grow then the next time I’m on the mainland I’ll try to find the ispring version and ship it to myself. TBH I don’t pay a lot for water but it will bother me to waste so much when I can do something about it.
Thanks for all the help. When I get to a solution I’m happy with I’ll post some kind of reply here. It takes me a while though. Having things shipped to Hawaii means it takes a minimum of 2 weeks to get the this stuff.
I’ve had some time to play with this now so I want to summarize. First, sodium really is a problem. For me the most compelling point is from @MidwestGuy:
“I wouldn’t worry about it unless you see sodium toxicity symptoms (which will present as deficiencies.) Sodium is a salt that will submarine your grow media pH and may inhibit nutrient uptake.”
There are times when I search the internet trying to figure out a problem. I think what he is saying is that too much of even an inert solid can disguise problems. That’s important to me.
Next, my township does have an RO water vending machine. It runs about $0.40 per gallon. The price isn’t the problem, the schlepping is more of a problem. Also, when I test this water the TDS is about 125ppm. It’s not clear whether their filter is defective or if they are deliberately adding calcium and magnesium. Either way I decided not to use it.
I cancelled my order for an RO buddy and bought this:
My reason is the amount of waste. The advertising for this one says it reduces waste substantially, and as a bonus the speed is faster than an RO Buddy. My experience is that the advertising is accurate. I’m not enough of an expert to make a recommendation, but I will say I am satisfied with this purchase.
My goal to fill bottles with a daisy chain was deceptively difficult but for me, probably worth the effort. I’ve been using 5 gallon American Maid water bottles from Walmart to mix nutrients, and I wanted to daisy chain them together so I didn’t have to check on the filter as much. The key to making that work is this gizmo:
If you can get two of these installed in a water tight way then you can daisy chain the bottles. This was a bigger hassle than I expected, but here’s an approach that does work.
First, you have to use the round bottles, not the square ones from Walmart. The round bottles are stronger. If you use the square ones the pressure will build up at the start of the chain and destroy the bottle.
I didn’t want to weaken the bottle at all so I install them in the cap. The caps that come with the bottles are not very strong. It’s really hard to drill them without cracking the plastic. So I used a 3d printer to make a beefed up cap that looks like this:
The holes are the right size for the fittings above. I install them using the threads and a hot-melt glue gun. Everything about this cap must be strong and water tight to work. There is a small groove on the inside of the cap which is sized for this:
This is just to make the seal as tight as possible. With that created you can just daisy chain the bottles with RO tubing. The tubing and fittings are quick-connect, so I set this up and make enough water for a week or so, then tear it down and put it away.
The ispring filter takes about 7 minutes per gallon, so 10 bottles takes just under 6 hours. I thought about putting a float valve with a small tub at the end to turn it off automatically, but it only turns off when the pressure rises and I didn’t want to press my luck on the strength of the contraption, so I just set a timer and turn it off myself.
I assume there were easier ways to do some of this, but things are working for me now. Many thanks to everyone who offered suggestions!
I’ll admit to being nerdy and having some fun with my 3d printer, but I do find the bottles useful. Five gallons is about as much as I can conveniently carry, and it’s cool to line up a bunch of them and let the filter fill them one by one without my attention.
