New sand or add DE?

Last year I had a real tough time opening the pool (25Kgal ig vinyl). It eventually turned crystal clear but took 3 weeks. This year the same. the #s are 30 ppm TC, 7.2 PH and about 60 CYA. I'm stumped, the water is a light shade of green for 3 weeks now. I keep brushing and vacuuming. So I bring a sample to Leslies and the guy says I must need to change the sand (I've had the pool 5 yrs, never changed the sand, don't know about previous owners). Should I change it or add some DE as I've seen on some threads?

Try the DE first, but that is helpful for the filtering aspect, but if you still have green water, it sounds like the algae isn't dead. Which makes me wonder if perhaps it isn't algae. Wondering if you fill from a well and it could be a metal problem? Also, how many times a day are you testing and dosing with chlorine? If you are shocking it and then letting it fall and then shocking and letting it fall, it will take longer. You need to sustain the high reading by testing at least twice a day and 3 times a day is even better if you can do it. 30 ppm cl is pretty high for a vinyl pool with cya of 60.

I've been working on the pool every night (I'm at work all day, so I haven't been able to do it more often). It's municipal water so I'm going to try the DE, I'll let you know how it goes. Thanks.

When you get home in the evening, what kind of chlorine residual do you have left from the previous evenings chlorine addition?

My chlorine level has been so high I can't tell (it's been over 30ppm for the past week, with no CC, the guy at leslies confirmed). Once I got the PH level to 7.3 I kept adding bleach. Brush and vacuum daily, scratch my head in the morning. Same happened last year, but one day it just cleared up. I'm really hoping it's the sand. Another question: if the DE doesn't work and i decide to change the sand, how do I remove the top (I have a Hayward S240, i'm not sure if I unscrew the black cap on top, pry it off, or unbolt the rib around the middle)?

Looks like you would unbolt the middle. All the info is on their website at
http://www.haywardnet.com
including manuals, parts lists, etc.
You don't pry anything.
Al

Thanks, I found all the info I need. I'll let you know how it works out.

nyjobz,

FWIW, I have a 30' round pool with a 150lb sand filter. I too am in NY. Around here you have some guys saying that you should never need to change your sand, while others say you should do it every year.

My pool is around 5-6 years old. I decided to change the sand this year. The sand looked perfect for about 3/4's of the way down. Then, just under the little pipes, it was all dark, yucky, mud-like silt.

So, that tells me that it is a good idea, every few years at least to change the sand. My filter works well now.......it did before, but I have to believe it is better now.

Getting the "old" sand out is easier when you use a shop vac. Make sure you use the plastic sand filler thing to keep the center pipe "on center" when you refill.

Frank D.