I know fertilizer will lower the pH, but that's not my question - because often times we don't use fertilizer when watering, especially in the winter. So what do you do with the water when you don't use fert, but want the pH between 5.5 and 6.5 (or wherever).

I'm wondering if lemon juice is safe on orchids, and if the produce "pH Down" is safe? I've heard of people using both.

Thanks, JOHN

I fertilize (one X per week) year round, and I adjust the pH of my fert mix primarily with Protek (potasium hydroxide), and sometimes with Magox (magnesium hydroxide).

The rest of my watering is with RO water, which is about neutral when fully aerated.

pH down is usually some dilute form of phosphoric acid, which is probably as good as anything else to acidify water for orchid use.

I'd read others saying it was phosphoric, but in fact it's Sulfuric Acid - I'm looking at the label now. I bought some, then thought maybe I ought to ask you guys before using it.

I tend to do what Rick does - make a "soup" once a week that the fertilizer causes to go down in pH and then adjust it up w/ PRO-tect, and I use distilled or fishwater, or a mix of the two for the other alternate watering.

JohnDC

I would caution that anytime you raise or lower pH you esentially increase the TDS (salts). This is why I opted for the RO water for general watering needs.

But sulfuric acid is probably fine for what you need to do. It probably won't take much.

Vinager may also be a good choice. Thats primarily acetic acid, which I have heard is used by people growing Cyp. acule. Acetic acid is closer to some of the natural acidic breakdown components in compost (other than humic acids).

I spit in it.... Sorry I haven't moved to pH readings yet. It really confuses me. I do not measure my TDS either. Bad orchid grower....

Tadd, you are just so darn CUTE! :lol:

I don't measure my pH either. :embarass: Eventually I might get around to it just because I'm curious now. For tap water I think ours is on the hard side, definitely not softened. I did a little dance when my husband showed me the RO unit that came with our house! I use that to water all my inside plants which includes all my slippers. The problem with our RO unit is that it come through a small faucet on the side of our sink and the water pressure is much slower than the regular tap. I can fill a gallon jug and about halfway through the water is trickling. It's a little bit of a pain in the ass, so I try to keep a few jugs filled all the time so I don't have to fill them in one sitting. The outside plants get tap water with fert once a month. Nothing has died so far (at least not from my watering :unsure: )

To low down pH You may use citric acid and to rise pH KOH .This work suitable for orchids

I was really shocked the first time I tested the pH of my fertilizer. I use rainwater as much as possible and it was testing around 6 to 7. When I popped in some liquid fert it plummeted to 4! I'm just using an aquarium test kit so I don't know how accurate it is, but since then I've been adding back in some of my calcium-crunchy tap water to buffer when I fertilize. (Which, come to think about it hasn't been since July probably) Maybe I should look into that Pro tekt stuff I keep hearing about. I tried using the aquarium kit "pH Up" but it took a third of the bottle to fix only three gallons of fert.

Mark
Your aquarium pH kit is accurate enough. The advantage to a meter is speed. With a meter you can make drop-wise additions of buffers and watch the pH change at the same time. Some buffers like magox and bicarb have a lag time though, so its easy to over shoot target pH with those until you get used to the lag. Protek (KOH) is fairly concentrated and fast reacting, so its fairly easy to use. As oposed to straight KOH, Protek also has a high silicate content, which can toughen up cell walls, and increase disease resistance.

I use Pro-Tekt in my fertilizer mix, to bring the pH up to about 6.5-6.8....my tap water is clean and neutral, so I don't adjust it at all. During the summer, I add some RD-20 to the water, which may raise the pH slightly..........The lower the phosphorus in your fertilizer, the less acidifying it is likely to be....and since P is generally a waste in fertilizer (I use the lowest P MSU formula...), its probably best to get a low P fertilizer. Take care, Eric