I would definitely let the tap water sit out for at least one if not two nights. I also aerate the water with a air pump/stone while it sits out. While there may be similar or better products, I use Ionic Grow Hardwater as it seems to keep the PH stable. By the way, my tap water is around 300 ppm 7.8 PH. I do use half reverse osmosis and half tap water. Using the Ionic nutrient, I don't have to add any PH down.

Thanks for the infromation!

I read up on the Ionic Grow Hardwater and it appears to be a really good product. I will pick some up and give it a shot.

You can use ordinary white spirit vinegar to lower the pH. Use a 5cc syringe to dose at ± 1cc/g for a full point down. This may vary depending on the composition of the water. So try it out first.

Vinegar, lime juice and etc do not control Ph well in nutrient solutions.

willard3 / anyone,

Do you know how PH is controlled in an "organic" system? Is it just a matter of keeping up with it more often by using citric acid or something, or how is this done? I'd love to compare and see how this is done without a chemical in hydroponics.

I know that Earth Juice has a PH adjuster but I haven't used it and the guy at the hydro shop said you'd need to use a lot of it - I don't know, I have no experience with this but would like to know for the future.

Also I am currently using phosphoric acid and it seems like I have to add more than the bottle says per each point drop - I don't know still trying to figure it out.

Here are some links about the Earth Juice products:

The PH adjuster (Natural Up and Down):
http://www.earthjuice.com/index.html

Hydroponics:
http://www.earthjuice.com/hydropon/index.html

Hydro-Organics:
http://www.earthjuice.com/hydroorg/index.html

The Earthjuice pH adjuster is probably an organic acid (such as: vinegar, citric acid or tannic acid). Tannic acid is sometimes obtained from oakleaf extracts.

Phosphoric acid is excellent as a hydro pH adjuster, but in my country it is difficult to obtain in smaller quantities, hence I use bicarb and vinegar as up- and down-adjusters. Been doing this for 6 years now.