Topping off a large sand filter

[framcus]

I am performing the spring start-up myself for the first time and checked the level in my sand filter, assuming that the pool company had never topped it off. I have a Pentair triton TR-140 and the installation and maintenance brochure is at the link that follows:

http://www.recsupply.com/Documents%5CPentair%20Triton%20II%20Manual.pdf

According to the brochure the headspace between the sand level and the top should be 13 ½ inches and in mine it is now 23 ½. I clearly need to add some sand.

No. 25 standard silica is recommended (uniformity coefficient not greater than 1.75) 0.18-0.2 inch diameter particle size.

I have 2 questions;

1. Would anyone like to estimate how many lbs of sand I need to buy? Since the total in a fully filled filter is approx 650Lb there is considerable room for error! Iplan to buy 2-3 large bags and see how far that takes me, but would rather avoid sveral trips.
2. What sort of sand is #25. Will it be a big problem if I add just regular sand? Would 'play' sand be any better?

Thanks

[darenjones]

Just a guess, but I would figure it out mathematically. How tall is your tank ? I would take that figure, divide it by the 650 lb, that will give you an approximate poundage per inch. At least get you close, so you don't buy 10 bags extra...
Just my 2 cents.
as far as the sand requirement, I am sure it has a lot to do with flow rate, and what the screens inside are capable of. I would defiantly not use play sand, as it is not sized uniformly.
Anyway, sure some others here that might know more will either correct me entirely, or add to my suggestions!

[thepoolman1]

It sounds like you will need about 200# of sand. When you add it to the filter, make sure to swing the diffuser out of the way so as to not get sand into it. Since it is difficult to determine exactly how much sand is needed, you should probably plan on two trips to a supplier, either buy too much and return the extra (or keep it dry and add some in a year or two) or go get what you might need and go get the rest later if it is not enough. Either way, since you have a filter with it's own fill port adding sand is relatively easy and sand is not all that expensive.

You MUST use sand that is designed for swimming pool use. DO NOT substitute any other or you will end up removing all of the sand in the filter and starting over. And, you will have 600+# of wet sand to dispose. Not an easy task.

[framcus]

Thanks. Very helpful advice. You're right that getting 650 lbs of sand through a drain hole would be a major pain!

Is there any difference between #25 grade and #20 grade sand? I would guess not, but all the advertised sand I have seen is #20 grade.

[kwong]

I'd use some kind of funnel mechanism .. that way you don't get any sand in the middle pipe area ... just my 2 cents. :)

[newbie2715]

I'd use some kind of funnel mechanism .. that way you don't get any sand in the middle pipe area ... just my 2 cents. :)

I used duct tape over the middle pipe... then cleaned it off. Fairly simple.

I am sure you know this but make sure the filter has water in it when you add the sand as to not put undue stresses on filter components.

[framcus]

Added 200 lbs of sand (good guess by the poolman) without mishap, although without the benefit of the last couple of useful tips, which were posted after the deed was done. Probably need another 50-100 lbs of sand to get to recommended headspace, but filter worked really well during the pool opening regardless.

Thought I would add some DE to enhance filtering (the well water used to top up the pool is full of iron). The cacluated amount of DE for this size of filter is 2-3 cups. This sent the pressure up from 15 to 30 PSI. I backwashed and it returned to normal. I assume this is too much of an increment. Any suggestions on optimal pressure increase to aim for?

Thx

[Watermom]

Aim for a 1 to 2 psi increase. It won't happen immediately - maybe a half hour or so. So, don't add too much DE too quickly or you will overshoot your target again.