Why does the suction hose for my pool filter collapse?

Question:I have a 24' about ground pool. It has a haywood 1hp pump. The problem I have is that when I use the pump and filter to vacuum the bottom of the pool, after a few minutes the suction hose collapses at the inlet to the pump. I have a new skimmer basket assembly because the previous owners didn't winterize the pool properly and it froze causing it to crack and suck air when I vac the pool. I also bought a new vac hose last year before I found the cracks in the skimmer housing. I use one of those clear triangle shaped vac heads with the brushes on it. I know I don't have any restrictions in the hose or the skimmer housing. I have backwashed the filter before I start vacuuming the pool. Could the vac head be causing the restriction? Should I try a different vac head? The suction and return hoses are new as of last year. They were removed in the winter. Could it be just a bad hose?

Answers:
There is an extra load on the pump when vacuuming as opposed to just filtering normally; the water now has to be drawn through all that extra hose as well.

A couple of things to look at:

What diameter are the hoses? Above-ground pools (and Hayward equipment) can use both
1 1/4" diameter and 1 1/2" diameter (for both the filter and vacuum hoses). Use the 1 1/2"; it offers less restriction to the water flow. And how long is the vac hose? Too long of a hose can cause your problem. (Anything under 30' or so , 1 1/2" diameter should be fine.)

It is very unlikely that the vac head is causing the problem; that is one of the best vac heads on the market. Besides, it is clear, and you'd see the restriction. Something could be blocking the vac hose; to test this, hold the end of the vac hose over the return and see how strongly the water is flowing through it.

I would suggest trying to replace the hose that has the problem if everything else checks out. The main reason for this is once a hose does collapse like that, it is weaker in that area. It will likely continue to do that even if there was another cause of the problem that was removed. (Happened to me recently on my Aqua Critter hose.)

Addl.

The valve on the inlet side really wouldn't do much good. You don't want to restrict the flow into the pump. I would recommend changing the hose from the skimmer to the pump (that's the one, right?) It's probably just been weakened. It happens... Try to get some of the better-quality filter hose. Some of the crap they sell these days (the bulk hose they cut in the store) is generally too flimsy and doesn't last very long.

Ideally, the best thing to use is 1 1/2" PVC (flexible or rigid) if you can...