The Quality of Water: Beating My Dead Horse

[WaterWitchin]

Borrowing a style of titles from DirtyC. Because I like to steal good ideas. With some new/different faces around, I want to discuss (yes, again) rain water vs RO water vs tap water.


About a year and a half ago, my curiosity was piqued by someone's post, and it ended up being a fascinating story about a guy named Brandon Tam. Water Quality Questions

Then yesterday, estación seca made a comment on a thread, and started me thinking again: "My Phrag. QF Maria was eaten by rats. Before that it grew easily in semi/hydro and flowered a lot, even with my alkaline mineral-laden city water."

Which made me start thinking about water again, as I spent many summers close to the area where ES lives, and remember what that water tasted like. (No offense, ES). And how he was growing a phrag in that water, successfully. (other than pack rat invasion of course)

After I retired, 2016, I had more time to invest in taking care of my orchids and other stuff. I decided to try to start fertilizing more regularly (as opposed to a few times a year). I also took an RO system I'd had at the store and started watering my paphs, phrags, and a couple others with RO water. Then a couple years ago, started watering everything with RO water during the six months orchids are in the BatCave. The six months while outside, they get water pumped from my koi pond as they always have.

We're in the middle of 2020 now. I'm really not sure that overall I'm seeing that big of a difference one way or another. With a couple of phrags..."maybe." Or perhaps just because they've colonized for awhile, and they always look better that way.

I still find using RO water to be more troublesome than tap water, and still wonder if it's really worth it. My total TDS still runs around 300, total alkalinity around 100. The pH is usually a bit over 9. I do know that prior to fertilizing fairly regularly and using RO water, all the plants tended to get watered more often... much less procrastination. It's so easy to turn on a couple of water spigots.

I truly don't see the difference now vs four years ago, or vs 15 or so years ago. Or maybe I'm blind to changes. Am I jumping through unnecessary hoops? The only thing I know for sure is switching to semi-hydro, for me and my particular plant care philosophies overall, has become my best friend.

Your thoughts on what YOU do with YOUR plants where you can see worthwhile change for the hoops you do or don't jump through?

[DirtyCoconuts]

hmmm, i like this conversation a LOT.

I do not have a TDS meter and i want one and i don't trust my water report bc it reads like propaganda LOL

i have 110 gallons of rain water on hand for about 9 months of the year...i have noticed that in the last two years i cannot count on it for the three months in the middle of "winter" some times it rains and some times it does not.

during that period i spent a lot of time stressing about water and i ended up using my hose for everything except a few plants i knew to be picky and i noticed no ill effects.

i have since started using the hose on non-raining days for a flush or soak while still using the rainwater for my normal routine of spraying and feeding.

i think it works out to about 3 days of hose for everything, three days of sprayer with k lite and one day a week where i don't do anything bc it is raining too hard

[thefish1337]

I'm lucky enough that my tap is around 30-37 ppm TDS however the pH is 8.5. I never bothered with pH adjustment and just dissolved dilute fertilizer in every watering for around 5 years. One big change in the past year is that I started adjusting pH to 5.7-5.9 and I've had good results doing so.

Under my LEDs it appeared that some of my cattleya's were magnesium and or calcium deficient prior to this regime. One thing that I noticed when I acidify my water is that salt build up on LECA and media is less apparent. I believe that this is because calcium begins to increasingly form carbonate/phosphate/sulfate precipitates as you increase pH, it also will precipitate with particular anions at lower that pH 5.5. Prior to pH adjustment I would water my plants with 200ppm TDS fertilizer around pH 7.8. This effect will be amplified as your pot dries out. I consider most orchid growing to be hydroponic in nature and I personally grow in mixes that are dominated by inorganic components with little to no bark. There is a lot of misinformation or misinterpreted information about pH online because people conflate soil based research and hydroponic based research. You will hear people say "plants can adjust the pH with their roots/ it doesn't matter ect."

I have two responses:

1) it takes energy (ATP) for a plant to change the pH which could be spent on other processes.
2) if you flood (aka proper flushing) your plant with high pH water regardless of your medias effect, at least initially, the pH of your orchid pot will be dominated by the solution. this initial period is when orchid roots take up most of their nutrients.

When the raw water contains more than 180 ppm of calcium, the total calcium in the water can be deleted from the formula when preparing the nutrient solution if the pH of the solution is maintained at 5.8 to 6.0. If the pH is maintained at 6.6 to 6.8, only about half the calcium in the water can be considered available to the plants.

link to Texas A&M Horticulture extension

Another thing that cannot be understated is that plants love consistency. If your water isn't ideal pH or TDS but you provide consistent watering and good culture the plant's roots and microorganisms will adapt eventually- maybe the plant won't be growing to its full genetic potential but if adjusting your water to an ideal state is too much work or it results in less watering frequency or whatever then it becomes an obvious trade off. Personally, if I had more space I'd just make a big reservoir of tap water and acidify it with sulfuric acid because pH adjustment is annoying as WaterWitchin' has stated. However, the results I've had with pH adjustment have been positive.

[JScott]

Back when I kept reef aquariums, I had an RO unit, and so I also used RO water to water my plants. I eventually gave up the reef aquariums (I was moving around a lot at the time, and those things are a *expletive* to move). I continued to use the RO water on my plants, until my RO unit broke. I was faced with either going to the expense of replacing it, or just using tap water. If I was still keeping reef aquariums, I would have had no choice. Pure water is an absolute necessity for reef aquariums, but I didn't have any reef aquariums anymore, so I switched to tap water for my plants rather than buy a new RO unit. i noticed no ill effects, or any changes in the quality of my plants' health at all, so I continue to use tap water to this day. I've never looked at a water quality report for my town in DFW, Texas, so I have no idea how this water compares to the water in other places I've lived, but I didn't notice any issues when I moved here, so I think the water must be fine. I am only one person, and one person is not a statistically significant sample size, so we cannot draw any valid scientific conclusions from my experience, but i determined that RO water was more trouble than it was worth. I have been equally successful just using the tap water in whatever city I'm living in at the moment.

[hypostatic]

meh, I'll poke the horse a little bit too lol.

Short answer: It depends! (of course!)

Is your tap quality horrible? HOW are you using the water?

My tap quality sucks. I'm also running a mistking, basically to increase the humidity, especially in the winter. Evaporation was leaving a lot of calcium/lime salt deposits on my orchids... which most orchids are NOT a fan of. Switching to RO/DI quickly resolved this problem, and the health of all my orchids have improved since.

I ALREADY had RO/DI, since I need it for my reef tank.

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[SouthPark]

I think that a report of the water contents is a great start. And if there appears to be levels of particular elements that are way too much, then we should consider sorting that out (eg. if calcium carbonate deposits are obviously building up etc in the media), or if all the orchids are obviously not doing well - even when all other factors are satisfactory (humidity, temperature, air-movement, light, watering schedule, media state, etc).

If the orchids seem to be handling the tap water years on end ----- then that's very nice and convenient.

[Subrosa]

I have about 400 gal of rainwater storage and live in an area that gets lots of precipitation year round. Of course for about 4 months out of the year much of that precipitation is in solid form, and my rainwater is a large ice cube for most of the winter. My collection is geared towards Cattleya and other orchids that are ok with my 190 ppm tap water with several exceptions. In cold weather I reserve rainwater for those plants, but use it on everything when temperatures allow.

[SouthPark]

I forgot to mention one important thing ------ for ultra special collections - or collections of orchids where the grower aims to cut down on uncertainty about growing conditions ---- and maximise chances of long term orchid health and survival, then definitely ----- a nice stable reference for water would be beneficial ..... like RO water or distilled water ----- where the grower must process that sort of water (add elements) to get pretty much what they need or want ----- before using it to water the plants.

If this more-purified sort of water is going to be used, then growers just have to factor in cost, time, effort etc. I think that if it is worth it, then definitely go for it. We can always assess the situation later - like whether we really need to use RO. Sometimes - it might really pay to use that extra time and effort - for the benefit of particular orchids being looked after.

[isurus79]

I've got a 2,500 gallon rainwater catchment. Its great! Definitely beats the tap water around here, which is captured after it runs through a limestone aquifer.

---------- Post added at 09:26 PM ---------- Previous post was at 09:25 PM ----------

Also, Sue Bottom has a very in-depth article on water in this month's AOS magazine. Definitely worth checking out.

[DirtyCoconuts]

2500?!?? What sort of vessel holds that ??