Change Filter Sand after replaster?

[grasshopah]

My pool (ig 30,000 gal gunite) has just been replastered, and the pb s pushing to change the sand in the filter. I changed the sand in the filter
two years ago. While I have been battling algae all summer I am not convinced the sand needs to be changed as the pressure drops
back to initial level after very backwash?

what do you the gurus recommend?

Thanks

 

[duraleigh]

I'm not sure about the "guru" status but I have strong opinions about changing sand - DON'T!

Mine is 7 years old, never changed, and I don't plan on changing it.

You need to work on your algae issues by keeping adequate chlorine in your pool but the sand is irrelevant.

 

[PoolGuyNJ]

Sand can become contaminated. Sometimes after a homeowner have vacuumed a bloom but not sent it to waste,I scoop a couple inches off the top and add another 50 lb bag. Then I'll pour a gallon or 1-1/2 gal bottle of unscented bleach after refilling the vessel with water and let it sit for a couple hours, then rinse. If the pool reblooms again, something else is going on.

Scott

 

[duraleigh]

Yeah, that's a good point, Scott, and I see some common sense in that.

That might be helpful in clearing a badly-contaminated pool but I wonder if circulating shock-level chlorine until the pool cleared wouldn't have the same effect?

My thinking is your suggestion might make the algae-killing process go quite a bit quicker if folks are comfortable with opening the filter and removing and then readding the sand.

 

[PoolGuyNJ]

The curing process, with all the brushing is not normally a situation that requires a sand change. Monitoring the pressure in the tank is very important as backwashing will be required more frequently than an already cured pool.

Watch your pool chemistry! I check mine at least once a week. In 10 years, I have had one algae event. It will be even more important when your plaster is curing since it's more vulnerable to staining and scaling.

Raising chlorine only improves the killing and oxidizing capacity. An algae bloom on the floor and slopes needs to be vacuumed out to waste. If a substantial amount is in the filter sand and left, it will decompose and raise phosphate levels in the pool, becoming food for the next generation. Thus, the cycle begins.

Adding more chlorine does not remove dead algae.

Sand does wear out. It gets smoothed out and polished over time. This reduces its effectiveness. Depending on the filter size, flow and run time, expect anywhere from 5 to 10 years of life.

Scott
PoolGuyNJ

 

[grasshopah]

Thanks duraleigh & PoolGuyNJ for you help.