Newbie with MAJOR problem...

[MyBlueDog]

Thanks.

Question for the engineers/scientists: Wouldn't a main drain suction blockage at 6' underwater, and a pump surface side 2' above cause the pump to pull oxygen from the water.

My thinking is since water contains O2, that any blockage in the main drain would restrict flow, causing the pump to work at the same rate, yet pull O2 from the water at a faster rate than it actually sucks the water.

Make sense?

[JJ in Tx]

How about a air chisel like on this page,used very carefully of course.

[MyBlueDog]

How about a air chisel like on this page,used very carefully of course.

Can you run an air chisel underwater?

[JJ in Tx]

Never tried but was figuring that the "power" was all coming in thru the air hose and everything happening on/at chisel was exhaust from the operation. would make sure i oiled tool prior to and after use as well as run it a bit once it was out of the water to make sure it was "dry" before storing it.
JJ

[KurtV]

Thanks.

Question for the engineers/scientists: Wouldn't a main drain suction blockage at 6' underwater, and a pump surface side 2' above cause the pump to pull oxygen from the water.

My thinking is since water contains O2, that any blockage in the main drain would restrict flow, causing the pump to work at the same rate, yet pull O2 from the water at a faster rate than it actually sucks the water.

Make sense?

I don't think you can "pull" dissolved oxygen from water with suction. If you could oxygen from water that easily, you probably would have been using a device that does that instead of a tank for your dives. (There are some devices for diving that allow you to extract breathable oxygen from water but I don't think the methodology is simple suction.)

Trying to think a little out of the box, is there any way you could drill a hole in the concrete chunk, insert a lead anchor, thread a lag bolt into the anchor, and pull the chunk out with a big pair of pliers?

[mshumack]

Can you run an air chisel underwater?

yes, an air chisel will work underwater but you won't be able to see what your doing with all the bubbles from the exhaust (the ones I've seen all exhaust through the handle or body). If there was a way to vent the exhaust through a hose to some distant location ...

[MyBlueDog]

Trying to think a little out of the box, is there any way you could drill a hole in the concrete chunk, insert a lead anchor, thread a lag bolt into the anchor, and pull the chunk out with a big pair of pliers?

I don't know. I think I'm going to try to keep chiseling on it with a long screw driver and take my chances with air refills at the dive shop. What a nightmare. I really don't want to have to drain the pool, but that's what it's sound like the only solution may be.

**One note: When my skimmer level is nornal l(half way up with water), and the pump is set on main drain, the air coming into the pump seems to disappear.

I have a simple 2-way Jandy, turn on way for the skim, one for the main drain. It is a brand new valve. 1 week old.

This makes no sense to me.

Why would a correct water level in the skimmer (or lack thereof) dictate me getting air in the pump when the valve is set on main drain???

[KurtV]

**One note: When my skimmer level is nornal l(half way up with water), and the pump is set on main drain, the air coming into the pump seems to disappear.
...
This makes no sense to me.

Why would a correct water level in the skimmer (or lack thereof) dictate me getting air in the pump when the valve is set on main drain???

Maybe there's something to your theory about somehow pulling the dissolved O2 from the water...

More likely, the skimmer and the main drain are connected before the Jandy valve. I'm NOT a pool plumbing expert, but I know that skimmers can be plumbed with two outlets; one goes directly to the pump and the other connected to the main drain plumbing. Maybe one the builders will weigh-in and explain the reasons for that. If yours is plumbed that way, and the water is not at the proper level in the skimmer, the system could be sucking air in through the skimmer and into the main drain piping on the main drain side of the Jandy valve. (There's a picture of what I'm inadequately trying to explain about half-way down on the right side of this page:http://www.howibuiltmyownpool.com/mo...bing-first-day.)

One other thought, try a small brick chisel or the like instead of a screwdriver; much harder steel.

[waste]

Hey Dog and others! RE: turbulence from an obstruction causing air bubbles - yup, it happens, I had a customer 5 yrs ago who had air in his hairstrainer but only when he vacuumed. My first thought was a pin hole in the vac hose, but using ours produced the same result. A pressure test revealed no leaks, however we got lucky and relieved the pressure at the skimmer and a bunch of acorn remains perked up into the skimmer. It seems he had vacd up ~5 lbs of acorns the previous fall with out the skimmer basket in place - they all collected at the first 90. The pertinent point to this story is that if the obstruction is lagre enough and you are only using that line for suction, the turbulance 'cavitatets' the water, hence the bubbles in the pump. This could be what was happening in your pool if you were only using the MD. As for the skimmer being fuller correcting the bubbles, if the obstruction was large enough - I'd be like having the MD valve off or the drain plugged, more work for the pump and skimmer line. What I picture happened was, with the water in the skimmer a little low, the 'extra' suction made the water vortex, sucking in a little air which appears as bubles in the pump (or the suction on that line was strong enough to drain the water out of the skimmer before the pool water could refill the skimmer - same thing happens when the weir is stuck in the vertical position) The only thing that comes to mind on the ? of why more water in the pool (higher on the skimmer) would aleiviate the MD bubbling is that the extra pressure from the water is enough to increase the boiling point of water, it would seem that if my theory is right you were on the margin of having the problem. (That's as scientific as I get )
Kurt(good to see you again,how was your winter?) Some builders do plumb the main drains into the second port of the skimmer and use a valve they place in the skimmer to regulate the 2 suctions(IMHO - very stupid for at least 2 reasons, 1. If the skimmer line fails you'll have no suction from the pool until it is fixed and can't run the system 2. If the water falls below the skimmer, you can't run the pool). However, as there is a valve for the MD, it must be running on it's own (clogged) line.
Carl, I too thought of the dynamite route, but I figured Dog would want some 'closure' on the issue and it would be really hard to identify that particular glob of crete and the pipe it was sitting in amidst all the mud, crete chunks and plastic shrapnel
Dave, I should have had you write my tag line - 'Listen to "Waste"' - I like it

[MyBlueDog]

Waste/Everyone,

Three points:

1. I think you are dead-on with your statements about "cavitation", the main drain obstruction. Keep in mind, the MD is a 2", and all I could get inside of the drain when inspecting it was my pinky. It is solid rock there (less what I've busted out recently). When I have the MD 100% turned on, cavitation.

2. The pool is definitely losing more than 1/2 inch a day here in Florida, at 87 consistent temp, and 82 water temp, over the last 48 hrs. I have bucket tested this. I am pretty confident there aren't any leaks, as I've spent the last month hunting done tiny leaks and filling them with A+B epoxy. Even the light has tested fine after removing it.

3. Point 3: I'm starting to think the crete was put there intentionally to plug a previous leak. Luckily, I tracked down the original owner here in town, who had the pool installed in 1986, and I'm waiting (hopefully) for them to call me so I can ask: Did you ever have a leak in the MD (and hopefully they can remember).

One more thing: I'm gonna take another dive, plug the MD for 24-48 hrs and see if that affects the bucket test.

This has truly been a tedious bizarre one.