How to replace main drain and line to main drain?

[Geoffre14]

How can I replace my main drain and the plumbing line to the main drain?

We discovered our main drain was retrofitted with a 1/2" diameter black poly pipe, snaked inside the original 1-1/2" line. The drain works but I can't use it fully as the pipe flow actually cavitates due to rapid decrease in pressure at the filter basket back from 1/2" to 1-1/2".

To fix this, I am assuming I have to:
- dig out the drain line, digging up to 12' deep to the deep end (and run earth dewatering due to high water table)
- possible sawcut/jackhammer the concrete surrounding the main drain
- replace plumbing
- recast concrete using doweled stainless rebar (or Simpson Heli-Ties, or similar repair products)

This is a huge project. Am I making it more complicated than it should be?

 

[Oly]

Plug it and be done with it.

 

[Jimrahbe]

14,

Why? There are thousands and thousands of pools out there with non-operating main drains, or no main drain at all, and they work just fine..

Jim R.

 

[MinerJason]

It is a huge project, and my question would be do you need a main drain? Lots of pools don't have them and they work just fine. My pool originally had the main drain plumbed to my skimmer, and I never used it, partially because I didn't have (or even know about) a skimmer diverter valve. During my recent remodel I had to replace the skimmer which exposed the main drain plumbing. I considered running a line from the main drain to the equipment pad, as it would have been really easy to do, but instead opted to cap both ends of it and abandon it.

 

[Richard320]

Why do you want to draw exclusively from the main drain? If you're hoping to keep the pool clean by brushing stuff to the drain, you're going to be disappointed. I've tried, and nothing but a "swish" gets drawn in. If you want it to empty the pool, a sump pump is lots cheaper. If you've got leaks, plug it. There are lots and lots of plugged main drains out there.

If it doesn't leak, I say leave it alone. It will help a little with temperature stratification and mixing chemicals, and that's all a full-sized line can do anyway.

 

[Geoffre14]

Guys, I really appreciate the advice. Everyone appears to be advising to just abandon the main drain.

I thought a main drain was important for mixing? The pool is not small--33000gal, in ground, approx 12' deep at the bottom.

PS There is 1 skimmer and 1 return, no auto water leveler. But it does have an overflow pipe that I've never been able to 100% plug due to rusted inlet, with an invert elevation only 3/4" above the skimmer elevation, meaning even small amounts of evaporation cause the skimmer to stop functioning and the main drain becomes my only (inadequate) water supply to the pump until I can manually top off the water again.

We plan to resurface the pool anyway and redo the deck & coping. (It is a 50 year old pool that was previously in disrepair with flaking white paint and pitting concrete.)

Maybe the smart idea is:
- plug the bottom main drain
- plug the annoying overflow drain
- add an extra skimmer and return
- add auto water leveler
- resurface

Would you agree with this idea?

Edit: We are in NY and need to heat the pool occasionally, which might also be a reason to keep a main drain, to keep water temp mixing well.

 

[Jimrahbe]

Geoff,

Well, most pools do not have a 12' deep end, so having a working main drain might make some sense in your case...

If you could only have one or the other, I would opt for more returns rather than a main drain.. Many many pools only have one skimmer so unless you are having a skimmer issue, or just have more money than you know what to do with, I would not add an additional skimmer.. I would want at least 4 returns, so that you could cause the water to swirl, like a flushing toilet bowl, but of course very very slowly..

I would not want to be without an overflow, but it needs to be at the right height to keep the water level a little above the center of the skimmer mouth. I'd fix or replace the overflow.

Thanks,

Jim R.

 

[Geoffre14]

OK thanks Jim, you've given me plenty to consider. Wish me luck.