As Chem_Geek suggests the problem is probably something you added -- probably were TOLD to add. I'm coming up with 6,600 gallons (18' x 48" wall) -- if that's right, it might be easier and cheaper to drain and refill, than to try to fix the water.

Take your tap water to Leslies and have it tested -- if it is indeed low in calcium consider draining and refilling. Once full, do NOT add calcum hardness increaser and do NOT use shocks or other products containing calcium hypochlorite.

Do use bleach to start up -- 1/4 gallon of PLAIN 6% household bleach per dose.

Read the test kit page (my signature) and then get a test kit -- you won't be able to effectively manage your pool without one. Pools store testing varies from acceptable to totally random -- with bad, random results more the rule than the exception.

Once all this is done, and you have your pool up to speed with correct chlorine, salt and stabilizer levels -- you'll have to acid clean your SWCG plates before you put it back into operation.