Pool chemistry differences between gunite and fiberglass pools


New member
Aug 31, 2016
Visalia, CA
Hello All:
We recently sold our home in CA (where we had a gunite pool/spa combo installed 3 years ago) and purchased a home in WA state with an in-ground fiberglass pool in good condition. I've always maintained our pool myself and was wondering about the differences in water chemistry needs between the two. What are the ideal parameters for fiberglass? Also, the new pool has a sand filter instead of cartridge and I was wondering how often, and how much, backwashing is required?


Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Welcome! :wave: For chemical levels, you'll want to refer to:
For your filter, we recommend a backwash once the filter pressure increases by 25% from the clean baseline pressure. You can slo read more about that on:
Also see our ABCs of Pool Water Chemistry and let us know if you have anymore questions.