~Getting serious about water quality~

[orchid-asmr]

Hello everyone!

So in my last post about fertilizers, I'm finally down to get a bit more intracate with water quality.
I bought a TDS meter and a Ph meter, but unfortunately I cant afford a RO system yet.
Have the following measurements for my water (tap):

TDS w/o fertilizer: ~201

TDS w/ fertilizer(brand: Grow More: Orchid 20-20-20):

~251

Ph w/o treatment (no fertilzer or vinegar): ~7.3

Ph w/ fertilizer: ~6.2

Ph w/ vinegar: ~6.4

As recommended I use vinegar to lower my Ph and it pretty much does the trick and havent seen any negative effects on my orchids which is a mixed collection.
just wondering if these are good for watering at the moment.
I also have about half of my orchids in S/H and the other in bark. Just wondering if the TDS are ok mainly, I feel like they are a bit high. I also find it odd that the TDS is only raised by 50 w/ fertilizer. Are these measurements ok or if not is there a way to lower them?

Also I've been looking at Epson salts to supplement my orchids? Any thoughts?

[camille1585]

Can't help much with the technicalities, but I do think that 250 (ppm, I assume?) is not that high. Be aware that if you got a cheap meter, or didn't calibrate it properly, the measurements may be off.

As to adding epsom salts, it would mostly depend on your water. You can usually find the water analysis reports online, on the website of your water company. In my case I learned that my tap water is fairly high in Mg, so no need for epsom salts.

[Orchid Whisperer]

/\ What Camille said.

I would add that "good enough" water quality depends on what you are growng. Hybrid Phalaenopsis and Brassavola nodosa are likely to tolerate higher TDS than Disa or Phragmipedium, for example.

I second her advice on cheap pH and TDS meters. A "TDS meter" actually measures electrical conductivity (EC), then estimates TDS from EC. For pH, you are just as likely (possibly more) to get useful pH results from pH paper, rather than a pH meter that can't be calibrated. If you can calibrate and temperature-correct your meters, and have EC calibration standards and pH buffers, your meter will be more useful than one that can't be calibrated.

As Camille stated, for public water supply, go online and look at your water utility's website. They should have water reports available, and the data they collect should include pH, TDS and EC, hardness, alkalinity, and Ca and Mg content. If not all of that data is online, ask the utility, they probably collect the data, but may not post all of it.

Last week I gave a presentation to the Northeast Georgia Orchid Society (NGOS) on water quality for orchids and interpretation of the essential measurements that I listed above (in as much "plain language" as possible). I hope to make presentation information available through Orchidboard, possibly this weekend.

[orchid-asmr]

mainly growing hybrid phals, with a few species, hybrid catts, some phaps, Lc., and dendros.

The Ph meter i have can be calibrated which i have, but the tds meter i have i guess could be cheapy but i knew this when buying it and assumed it wasnt going to be the most accuate but get the job done.

I looked up some info on my water and said

Ca 32-90 mg/L

Mg 10-24 mg/L

TDS 192-358 mg/L

Ph 7.0-8.4

K 3-5 mg/L

[AnonYMouse]

Originally Posted by orchid-asmr

I looked up some info on my water and said

Ca 32-90 mg/L

Mg 10-24 mg/L

TDS 192-358 mg/L

Ph 7.0-8.4

K 3-5 mg/L

Can you recheck your unit of measure? mg/L can't be right. Did you mean ppm?

[orchid-asmr]

this just shows ph, ca , and mg but i dont see ppm just mg/L.

its kinda why i got my own meters because i just found this info to broad. ive tried looking for more concise water quality reports but havent found any yet but still looking

im not sure how to make the picture bigger sorry if you cant see

[Orchid Whisperer]

Milligrams per liter (mg/L) is equal to parts per million. Either is fine.

You are higher than what is desirable (<200 mg/L) for TDS. Not too unusual in California. Your water includes Mg, so I would not add Epsom salts unless you see magnesium deficiency symptoms.

Your pH is not unusual for tap water. That could be natural, or could be adjusted by your water utility to minimize pipe corrosion. It is higher than desirable for plant nutrient uptake (best if pH of the water going through the root zone is in that 5.5 to 7.0 pH range). Check after you add fertilizer, which could change the pH. Gradual pH reduction can be achieved with gradual addition of vinegar or lemon juice (per gallon, literally drop-by-drop).

With the tap water you have, you may want to flush thoroughly with higher quality (low TDS) water, such as rain or reverse osmosis (RO) water. Or dilute your tap water with high quality water. Consider getting a reverse osmosis unit (there are countertop RO systems available).

Your Paphiopedilum are probably the most sensitive of your plants to high TDS.

[Optimist]

Originally Posted by orchid-asmr

but unfortunately I cant afford a RO system yet.

One of our smaller supermarkets has an outside RO water dispenser-- at 25cents per gallon. I bring my 3 gallon jugs down there for a fill.

Perhaps if you look around you might find something similar? It says drinking water, but if you read the signs it is RO water. I took a PH on it and it was 7.0. Very clear.

Also I obviously do not know where you live, but rain-water is cheap and abundant in many areas. If you own your own place better.

There are ways of getting clean rain water without asphalt from asphalt shingles. Mainly by creating a pergola with a metal or fiberglass pitched roof and harvesting rainwater in buckets or a small pond (Or farm-store horse trough).

Rain barrels can be cheap to buy. Often you can find big plastic barrels that have not held any toxic chemicles on cragslist. There are also rain barrels that are large sturdy plastic bags. (Sort of like the plastic used for sand-bags).

Best wishes!

[Ray]

Originally Posted by AnonYMouse

Can you recheck your unit of measure? mg/L can't be right. Did you mean ppm?

mg/L IS ppm when talking about stuff in water.

While it's not precisely correct 1 mg in 1L (1kg, 1000g, 1,000,000 mg) is close enough.

[Roberta]

I would't worry much about the water... for southern California 200 ppm is actually quite good. i have successfully grown a wide variety of orchids with water in that range (sometimes a bit higher, and pH closer to 7.8 until adjusted with vinegar for about 20 years. I got an RO unit last year because I wanted to go the "next level" with some of the pickier orchids like Pleurothallids, Sophronitis, and Den. cuthbertsonii. But for most Catts (except Sophronitis), Cymbidiums, Paphs, Oncidium, Australian Dendrobiums, etc etc. that hard water is fine. Note that the Huntington Library and Botanical Gardens grows Paphs in local well water that ranges from about 300 to nearly 600 PPM. Phrags and the fragile little rain forest orchids get RO water (cost is not an object there) but lots of things do just fine with that hard well water, so that is what they get, Until you get farther down the "orchid path" don't overthink this...