PH/TA Can't seem to balance. Help.......

[glogan]

We have had our pool for about 15 years. This year I can't seem to get the pool up and running. The TA and PH are low. I add Alkalinty Up / Soda Ash (Leslie's Products) and although it comes up it will not stay up. When I get TA and PH balanced I hit it hard with Chlorine but by the next day the Chlorine is gone and the TA/PH are low again. I have vacuumed, brushed the walls, backwashed, changed the sand and still have a green pool with unbalanced chemicals. Any help would be appreciated.

[chem geek]

If it's clear green, then this could be copper so have the pool store check for metals. If it's cloudy murky green, then this is more likely algae and you need to maintain a high FC level relative to the CYA level as described in Defeating Algae.

I don't know why the pH and TA are dropping so much unless you are adding some sort of acid. For example, is the chlorine you are using Trichlor powder or Dichlor powder/granules? These are net acidic when accounting for chlorine usage. You should instead be using unstabilized chlorine such as chlorinating liquid (or bleach).