Mission accomplished - new swimming pool filter+pump

Now that my back has recovered from what seems like digging out the Suez Canal outside our Gite, I can now write about the "fun" we had fitting the new sand filter and pump to the swimming pool at our Brittany Gite.

I wrote a week ago of having packed the car ready to go to the Gite, with the main task for my 3 day trip being to install a new sand filter and large pump in place of the little Intex pump that used a paper filter that we've used previously.

To help me with the task I'd enlisted the help of Geoff the plumber who had previously installed a new oil boiler in the Gite and a wood burner in the second house that we're slowly renovating.

First task was to decide the location of the pump and filter and then plan the pipework to and from the pool. The obvious place to site the pump and filter was inside our barn as there's electricity already laid on in there and we quickly concluded that it'd be better to dig a trench and bury the pipework under the gravel driveway so that people (and cars) wouldn't trip over the pipes and damage them.

We had some false starts with trying to lay out the positions of the pipes and it was early on the first day that Geoff reminded me that I should have bought some 45-degree pipe bends as that would have made it easier to position the pump and filter exactly where we wanted to. The debate over whether I had brought enough pipework and pipe bends and connectors continued for most of the next two days and whilst I'd *thought* I'd brought more than enough with 5x 3m lengths of pipe and 10x 90-degree bends and 10x straight pipe connectors, we ended up with only just enough of both the pipework and all the joints that I'd taken over to France. No doubt 45-degree bends would have helped as well.

Peeling back the weed-proof membrane and moving the gravel off the drive was the easy task but digging out the trench to lay the pipework in turned out to be a mammoth job that took us together the rest of the first day, myself then Thursday evening up to 10pm, and then the pair of us most of the next day before we'd got all the groundwork prepared.

We needed to dig a trench deep enough so that the flow and return pipes to/from the pool would be sufficiently protected under the ground, and as there was a couple of inches of gravel to go back on top we decided that about 4 inches down should be enough, but we also needed to dig the trench big enough to lay a drainage pipe to take away water from the sand filter when it was set to "back-wash" the sand.

I had some 65mm yellow perforated agricultural drain pipe that we used to take away excess water from behind the retaining wall next to the barn, so this was perfect for the job as the holes along the length of the pipe would let the water drain away into the ground. Whilst digging we were doubly lucky in finding that a 75mm yellow drainage pipe had already been laid straight across the front of the barn about 3 feet out from the building so by using a T piece of drainpipe and lashings of silicon mastic to fill in the gaps caused by the differing sized pipes, we were able to T the sand filter drain into the existing length of drainage pipe which would mean that waste water would be dispersed to soak into the ground over a decent length of the driveway.

The major challenge though were the rocks we found.

From other groundworks we've done at the Gite we've found a plentiful supply of large rocks, so much so that all of the flower beds are now lined with boulders that we've dug up from the ground. I knew we'd find a few rocks in the way of the trench but the size of them surprised both Geoff and I and getting some of the rocks out of the ground was a complete nightmare as they were physically too big and heavy to lift even with two of us.

We tried bending the pipe slightly to avoid some of the larger rocks but on Thursday afternoon we found the pipework trench was blocked by a rock that must have been 20 inches wide by 30 inches long by 18 inches deep. There was no way we could go round it, it was too big to go under, and we tried drilling into it in the hope that it would split, but no luck there either. It just had to come out of the ground !

In the end with a bit of lateral thinking we came up with a plan that must have been inspired by the Egyptian pyramid builders. Using a long piece of 2 by 2 timber and another rock I was able to insert the timber slightly under the edge of the rock and lever it up just a bit. Into the gap Geoff inserted a sawn tree branch log from our woodstore from when we had our oak tree pollarded last year. By wedging the branch under the rock we were able to prevent it dropping down slightly into the hole.
We then repeated the same exercise, again lever the stone upwards, insert another tree log underneath, and again the stone would be raised a little higher and prevented from dropping back down into the hole.

Repeat the exercise little by little, inch by inch, log by log, until we had the rock raised up above the ground level and then with great difficulty we were able to roll the rock onto the driveway leaving a massive hole in the ground where it once had sat. We got better with this technique as the trench progressed but it was still hard physical labour and took quite a while to get the rocks out of the ground in this manner. It also took an awful lot of wood and counting up afterwards we found it had taken 40 logs individually wedged under the rock to get the stone out of the hole.

Eventually by late Friday afternoon the groundwork was complete and we could lay the pipes, glue them all together, dismantle clean and check that the pump is all working (phew it was), then fill up the sand filter with the 5 bags of sand I'd brought over, and finally remove the stoppers from the swimming pool to fill the entire system up with water and check that it worked and didn't leak.

But we were not to be so lucky. As Friday afternoon wore on into Friday evening we found drip after drip, leak after leak in the pipework joints that meant that we had to put the pipe stoppers back into the pool, drain down the pipework, cut the offending section and re-glue the joint back together again to fix the leak. We managed to finish the job in the end having just about used up our entire stock of straight pipe joints in the process.

The problem in the end turned out to be the solvent glue we'd used on the pipes and joints. I'd had a bottle of glue left over from previous plumbing jobs and as it was still flexible we'd used that rather than buying new. In hindsight this proved to be a poor decision as the glue was obviously "going off" and when we turned the pump on it managed to find every weakness in the joints. The new pump has a lot of work to do to push the water through the sand filter so is a beefy 1 horsepower pump = leak city Brittany !

Eventually we managed to find and fix all the leaks, then we found that the rubber seal around the top of the sand filter was also weeping under the pump pressure so it took several more attempts including part of Saturday morning before we fixed that problem as well. We needed to be able to remove the top off the sand filter to change the sand every few years so we couldn't permanently fix the top into place. PTFE tape didn't do the job and nor did gas PTFE tape, so it came down in the end to using a semi-flexible sealant (a bit like Plumbers mait) that Geoff normally uses on gas pipe fittings before we got a completely leak proof system.

Then we "just" had to fill in the earth into the trenches, but this required a couple of wheelbarrow loads of extra earth to be dug up from the far end of the garden to fill in the holes left behind by the vacated stones, then carry/roll/distribute those same massive heavy stones around the edges of the flower beds, finally lay back the weedproof membrane, gravel and job done!

And it all now works perfectly, the pump hums away quietly and is definitely pushing the water round faster than it did before and the filter seems to be making quite a difference; when I left on Saturday the pool was getting clearer already.

Actually its not all quite finished. Because we didn't have any 45-degree pipework bends it meant that the flow and return pipes couldn't be "tucked back" to the side of the barn and so we've left some of the pipework visible until I return back to the UK, can buy some more joints - including some 45-degree bends - and then post them all over to Geoff who is going to adjust the pipework run and then fill in the remaining hole in the ground that you can see on the photo above.

And then 2 days after we'd finished the guests that were in the Gite called to say that one of the feeder tail pipes that connects the new pipework to the pool had sprung a leak and Geoff had to go back and replace it. I've ordered some new stronger flexible pipework which I will send off to Geoff in a day or so.