Using RO water worth it?

[Hootenanny]

My current water out the tap comes out at 290 ppm. I dont add a cal/mag supplement. Simple house and garden a&b..

Can someone with alot of experience tell me if its worth the extra effort of using ro water?

I have a ro unit already in the house, its for evaporation top up on a marine aquarium.

 

[Chris Scorpio]

pH is a big factor as well as the medium yer growing in

290 is pretty high

 

[Old Salt]

If you have it, use it. There's not much extra effort involved if you set up a container with a float valve. Add a pump for easier use.

I had my well water tested. The arsenic alone was 10X the allowable limit. There were many other compounds found that I really don't want to consume. Plants tend to concentrate the compounds.

If you take a look at the requirements for private wells, and municipal water supplies, you may find a discrepancy. Here in Canada private wells are allowed zero coliforms. Municipal supplies have a more relaxed standard. Water line work often allows bacteria to enter the supply. Municipalities also add chloramine to the water. Reaction with other chemicals in the water can produce toxins 300 times as deadly as previously when they used chlorine. Whether on a private well, or municipal supply, I highly recommend using an RO for at least all of your drinking and cooking (and growing).

In this day and age, don't throw the waste from the RO down the drain. Use it to wash your car, water the lawn, or flush the toilet. You'll save money on your municipal water bill.

 

[Hootenanny]

sorry i should of added that I grow in coco... I dont have any ph / ec testing equipment just the tds meter that came with my ro unit. I think I will look into the float valve idea.

 

[Hootenanny]

should probably look into a ph & ec pen as well...

and maybe some kind of weather station so I can see what my temps and RH are...

 

[Old Salt]

I grow in coco coir & perlite too. pH control is a must. I use 5.8 in veg, and 6.2 during flowering. Each plant takes about a quart or liter per day during flowering.

Don't forget calibration solutions. I calibrate my low cost pH meter before every use, and check every batch of nutrients. I use full strength pH down for batches greater than 10l and 1/4 strength below that. I dispense the pH down with a dropper bottle. It only takes a drop or two to get to a pH of 6.2 for flowering. Veg takes 5-6 drops for 18l. I use 1, 5, and 10 ml oral syringes to measure the liquid concentrates (General Hydroponics Flora Trio). In Canada you can get them free at any pharmacy if you get 2-3 at a time. Since the syringes don't reach the bottom of the retail containers, I use 100ml HDPE bottles for mixing the nutrients. I weigh the water to get the volume within about 0.1% for an 18l batch. I use a 100 X 0.01gm scale to measure out the dry KoolBloom. I use a long handled spoon from a wine kit store that I drilled 3/8" holes in to mix the solution.

I only check TDS/EC once a month at the RO. If you are careful mixing your nutrients, you don't need to check the solution.

Tap into the RO before the de-ionizing filter if you have one for your aquarium.

 

[Hootenanny]

Thanks Old Salt for such a thorough reply.

Why skip the last stage on the filter? will tds be low enough at that point?

 

[gr865]

Wish I had 290 ppm, mine is 790 ppm, city water, state limit for drinking is 1000 ppm. Don't drink or cook with it, just wash dishes and clothes, shower but rinse with rain water when I have it.
For grows, I use both RO (purchased per gallon) and rain water, both are < 5 ppm, add Cal/Magic to get the ppm to 120 before I add base nutes. Thinking of buying an RO unit, but want one that works well and is 1:1, RO:Waste. I use about 15 gallons/5 days in flower. I run straight coco in Smart pots, 5 plants on screens, vertical grows. Did a few horizontal grows recently and ready to grow vertical again, should start my next grow later this month.

 

[Old Salt]

Why skip the last stage on the filter? will tds be low enough at that point?

The TDS should be below 20 ppm after the RO itself. It will have removed at least 80% of the crap in the water, usually 95% or more. The rosin beads used in the de-ionizing stage are fairly expensive and have a rather short life span. I only use them when absolutely required, for example water used to make colloidal silver solutions. I'd also use it for aquariums

 

[Mayne]

walmart, if you have one, 0.37 cent a gallon, worth it if you have a couple plants, other then that, buy a Filter, $180, Growboss, best in the market,

 

[gr865]

Get mine at Watermill Express, $0.25/gal.

 

[Old Salt]

Check out Aquasafe Canada. I've bought several systems from them over the years. Their bundles are the way to go.
Their Home II 5 stage system bundle with a TDS meter, PSI meter, and six complete pre and post filter changes runs $389.82 CDN or $292.37 USD. On municipal water supplies it's good for 3-5 years. On a private well it's good for 8-10 years. I only need to change the filters every 2-3 years, as the carbon filters aren't destroyed by chlorine/chloramine. I also use a whole house 5 micron filter in front of the RO that saves on the RO pre-filters.

I pull water for growing after the membrane, not after the post filter. I also toss a spare membrane in with my orders to save shipping costs for an extra $53.62 USD.

 

[seriousburner]

No. Your plants have the same mineral requirements that you do and that includes chlorine/chloride.

 

[seriousburner]

I should add unless you have really hard water, then no

 

[Hootenanny]

Brought a ph pen and did some experiments.

The way I was mixing nutrients with tap water had the ph at 6.5... just in range. Explains why I've seen deficiencies early on but they go away later on.

8L of RO mixed with H&G A/B @2.5ml/L = ph of 4.1
6L of RO mixed with 2L Tap water + H&G A/B @2.5ml/L = ph 5.8
5L of RO mixed with 3L Tape water + H&G A/B @2.5ml/L = ph 6.2

So somehwere between those last 2 = Happy Days

Not sure yet how different nutrient ratios will affect ph but I will work it out as I go. Should equate to some plant health improvement being closer to desirable ph and having a lower starting ec.

 

[Old Salt]

Water from an RO should be at pH7.0. The nutrients do have an effect on pH. I use the General Hydroponics Flora Trio. The veg stage drops to about pH6.4, and bloom stage to a pH of 6.2.

I'd check the pH and TDS of the water coming from the RO.