PH and EC Relation

[omerizm]

GpsFrontier, Thanks for the help.

1. I'm preparing my own mix, all water soluble and used commonly in hydroponic systems. And I'm using a common formula, no problem there.
2. HCl
3. Tap water, not very good. EC measured at 0.6 I'm thinking about buyinh a RO unit.
4. Temp varies between 22-28 degrees celcius.
5. 25 gallons of water for about 50 heads of lettuce.
6. Lettuce, at different stages of growth from mature to seedlings.
7. My tester is accurate and calibrated, no problem there.
8. I adjust them to 6.0 and sometimes it jumps to 6.2-6.3 within a day.

[GpsFrontier]

First I am not sure what HCl pH adjusters are or even how to go about looking them up, a link would help. Tap water can be a problem, EC is not a good measurement of water quality. EC (electrical conductivity) cant tell you what is in the water, it just tells you the total electrical conductivity of everything that is in it combined. It cant break it down for you.

(I have a dollar in my pocket, does that mean I have a bill, 4 quarters, 100 pennies and/or any combination, all you know is that I have a dollar total.)

RO is good, but expensive just for a few plants. EC still cant tell you much there either, but at least you can be sure that most all the contaminants and excess minerals are filters out. nutrient temp should be good if it never gets higher than that. 25 gallons seems a bit small for 50 plants. Are you needing to add much replacement water to bring it back up to the 25 gallon level? Is that water pH adjusted? Lastly a .2 or .3 change is not something I would worry about. Lettuce should do fine between 5.5 to 6.5. If it slowly rises you can set it low at 5.5 and let it rise to 6.5 before re-adjusting.

I would go with a larger reservoir, and better water quality (If you can). Also I didn't ask but changing the nutrient solution helps too. The larger the reservoir, the less you should need to change it (due to nutrient depletion). Nutrient depletion can also be a cause of pH changes, due to the change of elements/ions in the solution.

P.S. With commercial nutrients they would have pH buffers in it, with home made nutrients that's up to you. What's the pH of the tap water before you add any nutrients at all.

[omerizm]

I change the solution every two weeks. Most of the plants are small and the system is closed well to minimize evaporative losses so there is not much loss of water.

HCl is hydrochloric acid. As far as I know, it is ok to use in hydroponic systems.

I know that we can not tell what is in the water by looking at the EC but it gives info on the total amount of ions in the solution. And tap water with an EC of 0.6 has a lot of stuff in it. Also I know that it contains a lot of sodium, a problem in my area. Sodium is not good for the plants.

My automatic PH adjuster is almost complete. Actually today I'm doing a test run.

[joe.jr317]

Yeah, HCl is fine for hydro. Do you have no way of collecting rain? If you could, that would be great and less expensive. It's also better on the environment considering the RO units lead to a lot of concentrated waste and are a waste of water. I know that they have improved, but just a couple of years ago the norm was that you wasted 2 gallons of water for every gallon you get in an RO system. And the membranes are expensive, too.

[omerizm]

I can not collect rain. Also here it does not rain much in summer months, when I need water most.

[Henry2010]

One thing to consider is that different elements are released into the nutrient solution at different PH's. There is a diagram of the elements and PH levels they are released at

Nutrient Acidity - pH | Homemade Hydroponic Systems