I spent the last week lurking around this board trying to find out how to connect my new Intex 1600 sand filter / pump combination to my 15 foot Intex pool. Since I've now set mine up (with the help of several separate topics here) I figured I would help out the next guy with the same problem by posting the details of how I did it.
This is a 15 foot 42 inch Intex pool and a Intex 1600 sand filter and pump.
The problem: How to make a round valve fit into a square hole?
The sand filter is made for larger Intex pools, so it has round bulkhead fittings for the pool outlet and inlet. The 15 foot pool I have has a wall mount skimmer, so while the inlet is a round hole in the liner, the outlet is a big square hole for the skimmer. There's a round hole cut through the bottom of the skimmer, with a cheap-o pump attached to it.
You can purchase adapters (here or here) on Amazon to convert the skimmer outlet to a slip fitting for the pump input. However, the adapters run from $10-$20 and are hit-or-miss. It appears Intex has made multiple skimmer models with slightly different sized bottom holes.
Fotunately, there is another way (suggested by others on this board)... use the pump that's already attached to your skimmer as an adapter. So here's the details of how to do that:
WHAT YOU NEED:
1) Everything that came with your sand filter, save 1 bulkhead fitting and 1 hose which you won't use.
2) Your original pump still attached to the bottom of the skimmer.
3) The original outlet hose that came with your pump.
4) An exacto or similar knife for enlarging the inlet hole in your pool liner
HOW TO DO IT:
1) DRAIN THE POOL. Drain your pool down below the level of the skimmer input. I did not drain mine fully, only so it wouldn't leak water out the open skimmer.
2) DISCONNECT POOL INLET HOSE. Your original pump hose is a corrugated plastic pipe with hose clamps sealing the ends to the slip fittings at the pump (under the skimmer) and the pool inlet. Loosen the hose clamp and remove the hose from the inlet only. Leave it attached to the pump.
[attachment=0:2z9c2rcg]original pump annoted.jpg[/attachment:2z9c2rcg]
3) REMOVE POOL INLET BULKHEAD. There's a T fitting on the back of the inlet that has to come off first, then the exterior bulkhead nut can be removed, leaving an empty hole in your pool liner.
4) DOES THE NEW BULKHEAD FIT? Mine was much too small, but some others have said they were able to get the new bulkhead to fit into the old hole without a problem. Test yours and see if it fits. Remember, the rubber gasket of the bulkhead has to be tight against the inside liner wall. If it's too large, take a Sharpie and draw a circle large enough to accomodate the new bulkhead. Place the center of the new bulkhead exactly in the center of the old bulkhead hole.
5) ENLARGE THE BULKHEAD HOLE. There's an extra-thick ring of liner around the bulkhead hole. Make sure your new hole isn't anywhere near the edge of that extra-thick part. Using a box cutter of similar knife, cut around your Sharpie line to make the bulkhead hole bigger. (Cutting my liner made me nervous too, but I didn't see any other way.)
6) INSTALL YOUR NEW INLET BULKHEAD. See the instructions that came with the sand filter. Once you enlarge the liner hole, it will install exactly per the instructions. Attach a one of the plunger valves (came with your sand filter) to the outside of this bulkhead. Connect one of the long hoses that came with the sand filter to that plunger valve.
7) SETUP THE PUMP & FILTER. Now complete the pump and filter setup, attaching everything except the input side of the pump. Install the 6-way valve and fill the sand filter. Connect the pump outlet to the sand filter input, and the sand filter output to the pool inlet hose you installed in step 6.
8) SETUP THE PUMP INPUT. Your old pump and hose should still be attached to the bottom of your skimmer. Locate the second plunger valve that came with your sand filter (you used the first one in step 6). Screw the theaded union on the valve to the input of your new pump. Connect the hose from your old pump to the slip fitting on the bottom side of the valve. Tighten the hose clamp to seal.
[attachment=1:2z9c2rcg]plunger valve annotated.jpg[/attachment:2z9c2rcg]
9. REFILL THE POOL. Remove the old filter cartidge from your skimmer, but put the strainer basket back in. Then refill your pool to at least halfway up the skimmer bulkhead. This pump pulls A LOT more water, so you'll need to keep the pool fuller to avoid sucking air.
TO CHECK BEFORE STARTING:
1) Make sure your 6-way valve is in the "recirculate" position. This will bypass the sand filter and just let you test your plumbing connections first.
2) Make sure both plunger valves are fully open. To open these valves, only the white tops turn. The black rings do not turn when the valve opens; they stay tight. (Yes, I screwed this up at first.)
3) Make sure the water line is at least halfway up the skimmer input.
4) Unplug your old pump. You are no longer using it as a pump. It's just a big T-fitting now.
5) Remove your old paper filter cartidge. You have a sand filter now, right?
4) Turn on the pump and hope nothing leaks.
5) Continue the instructions on backwashing and rinsing the sand filter before adding that into the mix.
OPTIONAL - REMOVE IMPELLER FROM OLD PUMP:
I went ahead and removed the impeller from my old pump. It's a small water obstruction, and I figured the fittings and hoses were already slightly smaller, so I shouldn't add any more obstructions.
1) Remove the pump from the bottom of the skimmer.
2) Remove the impeller from the pump. Procedure: Unscrew the 6 screws at the top of the pump. Take the top plate off the the pump base. Mine come off easily even though the pump was 2 years old.
3) The impeller is just sitting inside mounted on a magnet. Lift it out. It will come out freely.
4) Replace the top plate and screw it back down.
5) Put the pump assembly back into the base of your skimmer.
Hope this helps. I know the instructions are detailed, but one of the problems I had was pulling disparate snippets of info from multiple forum theads. So I've tried to get everything in one place. If you have the same setup and want more details about something, just ask and I can post additional photos. Good luck.