Well, from the several threads I've read on the subject, the best thing to do is knock the ph of my tap water down to the 5-5.5 range with vinegar. I'll have to do a little experimenting to see how much vinegar I have to add per gallon. So far I haven't had to do it yet because only a couple of things are planted, and mother nature has been keeping up with her doses of 6.4 on a regular basis.

FWIW - my TA and PH are higher than yours, my pH being up around 8.8, but I don't have much trouble outdoors watering from the hose, as long as I'm flushing the containers so I don't get (bi)carbonate build-up in the soil. In winter, even though I do flush the soil, I need to add a little Fe chelate occasionally or add vinegar to my fertigation solution every time I fertigate, which is every time I water. I just don't have time to do this in the summer because I don't have an injection system and I tend somewhere around 300 containers, so can't water with a watering can.

AL

what is the ph of your soil? before adjusting your water.

Al, thanks. Good to know. Maybe I'll play with the water ph a little if I have the time. At least I don't have to add too many chemicals when I top off the pool with the hose :)

terry, if you are asking me, I'm guessing that my 5:1:1 w/lime is 5.5 or so.

I did a little experimenting, and added 1/2 teaspoon of typical 5% white vinegar to a gallon of my tap water, and the pH dropped at least 1 full point, from 7.8 to a little less than 6.8, which is as low as my test kit goes. I was a little surprised at how little vinegar it took. Does this sound about right? Thanks.

Sounds reasonable. I'd shoot for a fresh tap water pH of just under 5.0 for containers because pH will rise as the CO2 gasses out.

Al

Do water quickly after you add the vinegar, also. Over time, the pH will rise as Al has indicated, so you're watering with 7 or 7.4 or even all the way back to 7.8 before you know it. If you test 24 hours later, you'll be surprised at how much it has risen.

I used to test it, now I just go by a few plants that are sensitive. When they start to lose their deep green color on the edges or veins, when my red backs disappear, etc., I know I need more vinegar. The water out of my tap varies from 7 to 8 over time; I'd have to test it every time to keep up. Looking at the plants seems easier.

I now just use 1/2 t per liter (so 2 t per gallon, approx) and water immediately. I haven't had any issues with leaf color in many months doing this.

Thanks. I'm planning on adding 1 tablespoon of 5% vinegar to my 2 gallon watering can whenever possible, and use it immediately. If I did my math correct 1 1/2 teaspoons will drop 1 gallon on water 3 points fron 7.8 to 4.8. So, 3 teaspoons (or 1 tablespoon) will work for 2 gallons. I really like science. The 5:1:1 is already paying benefits with the peas and potatoes I have planted. No matter how much it rains, 1/2" or 2", and we've been getting plenty of it, the water drains great.