get a big bag of baking soda from your local Sams or Costco it give directions on the bag.
if pH is less than 7.2 add 3-4 pounds of baking soda
if pH is between 7.2-7.5 2 pounds is needed
above 7.5 don't add baking soda
this is per 10,000 gal water
it goes on about the alkalinity as well
you don't NEED to use chorline which is unhealthy in itself...instead use GSE aka grapefruit seed extract or it's concentrate version
Grapefruit extract has been used extensively as an algaecide, bactericide and fungicide in lieu of chlorine in a variety of bathing and swimming applications.
Although the water clarity cannot be maintained as well with GSE as with chlorine, the healthful effects of this natural botanical extract, when compared with the unknown long-term effects of the absorption of chlorine, suggest that GSE be the germicide of choice in many applications.
Accordingly, where water clarity is not an absolute requisite, GSE could replace chlorine, but, unfortunately, at this time a test kit for detecting GSE concentrations in water is not available. Where clarity is more important, swimming pools, for example, ozone and/or hydrogen peroxide can be considered along with GSE. For practical purposes, therefore, GSE is most often used to replace part of the bactericide that is measurable, such as chlorine, ozone, or other commercial preparations. We recommend ozone for testing and clarity issues, along with 1-ounce of GSE per 2-300 gallons of water to kill the microbes that might get past the ozone. "
you can also use food grade 35% peroxide, don't have that info right in front of me, but a google search ought to bring it up.
I use GSE and baking soda with a filter in one of the big rubber pools and have no issues.
it also helps to have an one of them iondizers (sp), esp. if you have a "real" pool. do a google search for non-chlorine pool treatment, there are are some out there, a tad more costly, but healthier.