I think this is a Ph problem. Our tap water has a Ph of 9.2-9.3. About 3-4 weeks after planting rooted cuttings, the Ph read 7.3. I have been using liquid citric acid to bring it down, It is at 6.6 right now. Am I on the right track? Is the reddness caused by the improper Ph, or something else? On our Hanging basket geraniums, we are noticing a gray discoloration burn on the older leaves. There Ph is also high at about 6.8-7.0

Red margins could possibly be a nitrogen or phosphorus deficiency but if it's on the older foliage it could also be that the plants are being grown too dry and too cold.

If you were to have a tissue sample done you would probably find that the majority of nutrient levels are outside the recommended range. pH in a sense determines which nutrients are available to the plant. If the pH is out of the recommended range some nutrients are not as soluble to the plant while other might be taken up in excess, creating a plant that may be expressing a host of deficiencies or toxicities.

You are on the right track by trying to get the pH down. The alkalinity of your water will determine just how much acid you have to add to neutralize the pH. If you know your alkalinity you might want to check to make sure you are adding enough acid because it would be good to try and get the pH down to about 6.0.

It would also be a good idea to send in a tissue analysis to see exactly what's going on in the foliage. That way as you are correcting the pH you can also make sure your fertlity program is in check as well.