Let's call this a 'custom' siphon task.... ideas?

[SplashDIY]

I have other posts in this forum about the task of recovering this abandoned 25,000 gal pool with vinyl liner.

I am waiting on some final pieces of pump/filter equipment to arrive, and am tackling the first, heavy duty job - cleaning the pool without the ability to drain it more than say 30% (vinyl liner and associated risk of collapse).

My new 2" trash pump from Harbor Freight is doing a great job, as far as it can go. The limits to this method are set by the solids in the pool. I have given this a lot of thought. All leaf skimmer scooping is also limited, as the mix includes soupy, well rotted leaves. And it is smelly.

I am pumping down and then refilling with fresh water. But I'm not getting to the material at bottom.

The pictures show 2 versions of flexible drain hose. 25 ft and 50 ft, OD's of 4" and 4 ½" respectively. I am wondering - how could I prime these to simply gravity-siphon out the junk in the pool? I tried capping the downslope end of the 25ft piece, then filling the pool (suction) end with water. After putting that end into the pool, I tried releasing my 'cover' (plastic wrapped around the lower end). I did not catch siphon.

The advantage of this method is that most of the waste is just going to be pulled right through this much larger diameter hydraulic path, and it will be fast, too. A great way, potentially, to get most of the solids/soupy material out.

Are there any ideas as to how to make this work? While writing this, I came up with one more idea - start up my 2" pump, send the discharge back into an end of the proposed siphon line, while it is under water. I hope that it establishes a velocity of flow into the flexible line and that the siphon 'catches'.

Does anyone else have relevant ideas or experience?

Note to self : NEVER let a pool get into this state again. This was an unfortunate situation where the old pump equipment/controller failed, I was away for 5 months, and we have an overhead canopy of trees that makes this closer to a 'pool-in-forest' situation, than anything else.

 

[DrewLG]

how could I prime these to simply gravity-siphon out the junk in the pool? I tried capping the downslope end of the 25ft piece, then filling the pool (suction) end with water. After putting that end into the pool, I tried releasing my 'cover' (plastic wrapped around the lower end). I did not catch siphon.

With both ends of the hose open, hold the entire hose underwater and make sure all the air comes out of it. It may be helpful to have an assistant for this.

While the hose is still under water, cap one end.

Pull the capped end out of the pool, drag it downslope, confirm that the upslope end is still underwater, open the cap.

 

[SplashDIY]

Thanks Drew. Working alone, and figuring out how to cap one end is still challenging me. But I will keep thinking about it.

 

[SplashDIY]

While eating a sandwich - how about this? (Avoids any need to try form a seal on one end).

To be continued….

 

[bobloblaw42]

Saran wrap layers or other plastic sheeting + multiple rubber bands or zip ties?

 

[Lake Placid]

Get a cap like this https://www.lowes.com/pd/ADS-4-in-x...R7PxZQPP-kMnMJYv6ngaAkZfEALw_wcB&gclsrc=aw.ds

Or like this Fernco 4 in. Plastic DWV Flexible Cap PQC-104 - The Home Depot

While the whole tube is submerged underwater and full, cap up one end. Drag the capped end to where you want it.

 

[SplashDIY]

Thanks both of you for these good and innovative ideas.

bobloblaw42 - I had the same idea as you, and actually tried a heavy duty plastic bag wrapped and tied around the end. The force of the water column* was too great to be contained (I probably had more than 12 ft of loaded pipe below the level of the pool deck).

Lake Placid - thanks for revealing the existence of these fittings! Unfortunately, at the big hardware stores now, there are no employees in the aisles that could link a project goal to an avaiable fitting. And if you don't know the item (solution) exists, you can't ask for it.

... In the end, I did very well with a 2" (rigid walled) suction/inlet hose that is used for my trash pump. At 15 ft long, it was short enough to be manageable, but also long enough to be able to get the open end downslope. I managed to hold water in the open end (after filling it in the pool) by holding my palm over it. The flow rate was probably almost the same as running the pump itself, impressive to watch.

What this solution did accomplish was rapid discharge of water. What was left unsolved was removing what might turn out to be hundreds of pounds of rotting leaf material and twigs at the pool bottom (in my situation, a 2" opening would still rapidly clog up).

*One thing that you'll learn when you get up to any hose with a 4" diameter is that when a section of it is loaded with water, it quickly becomes so heavy as to be unmanageable. You could probably easily calculate how many pounds of water you are hauling around as you attempt to get the sealed end into a downslope position. To me, this large diameter siphon concept is worth further study, because it SHOULD provide unique bottom-cleaning capabilities when the circumstances are right. With this kind of oversized suction profile, organic material will be quickly moved. At 4" diameter, I can imagine concerns might turn to severe erosion of the land where outflow is landing.

Here is some further '3D thinking' about how this system might work - another napkin drawing attached. Further thought - there's no need for the end submerged into the pool to have a cap, but in the case of vinyl pools like mine, and perhaps all pools in general - some sort of cage over the submerged end would be important. My sense is that there will be a LOT of suction force at this end. It could destroy a vinyl liner in a second.

The key thing, once the hose is chosen is I think to have a slope available that you can work with. If the ground all around the pool site was at the same level as the pool deck, a way would have to be found to lower the open end into the ground - perhaps by means of a custom small trench cut into the grade?

When I am back at this 25,000 gallon pool, I am going to rig this configuration and report back it's feasibility.

One follow up question - does the outlet end of the hose need to be positioned only below the current water level of the pool, or instead down below the position of the suction side (inlet)? I suspect that it only needs to be kept below the current pool water level, but I will confirm this in aprox 2 weeks from now.

A footnote - I turned my attention back to my better quality leaf vac (brass hose fitting and heavier duty plastic body). I had not enjoyed wrestling with it initially, but this time I paid more attention to setting it up optimally - I found a more pliable section of hose to thread onto it's base, and then I tied this hose section to my extensible pole. Working blindly across the bottom of the deep end, I was repeatedly filling the overhead mesh bag within 1-2 mins, and I was able to carefully wrangle it onto the pool deck and unload it. Eventually the bag detached underwater, and of course the zero viz means it is going to be a while before I see it again. This is a marathon. I am reminding myself to be patient!

 

[Lake Placid]

Good info and thoughts to ponder. With respect to your question about level of the outlet….memory serves as long as the inlet side stays full of water (submerged) the outlet only needs to remain lower than the highest elevation of the hose (the injection port in your picture). I believe if the outlet side would be raised higher than that elevation than the siphon could be reversed. It will be interesting to see what you find in the real world test later on.

 

[SplashDIY]

Thanks Lake Placid. Some further development thoughts - this thing could actually be built out with rigid-walled pipe, eg DVW class. In 4", with 2 ball valves, I came up with a materials budget of around $200.

I am also reminding myself, one more time, that best move going forwards is to somehow make sure that the pool never approaches this state again! Once you are here - dark brown water, massive organic load hidden 8ft down - well, you're in uncharted territory. I will commit to having a pool cover installed before the fall (I have already made measurements and received a quote).