Using flows as returns...

[Jpadie]

I have a magiline pool where the skimmers have no suction line at all. There is only a return.

The return jet causes a low pressure to form below the skimmer and creates a flow through the cartridge therein. .

The system works fine in principle but the cartridge filters are madly priced (£150ea) and in my environment they need cleaning every hour when opening the pool (for a month...) And then every couple of days.

So I changed to a sand filter. Without realising that the skimmers have no suction line.

Today I tried connecting the return line to a skimmer to the suction. It worked after a fashion. I got flow from the skimmer and from the jet. Lots of nasty noise from the unit which leads me to believe that there may be a turbine in there that is leveraged for a Venturi effect. I had thought it used Bernoulli's principle but the sound does change the likelihood a little.

Anyway whilst this may solve the issue of getting suction through the skimmers (aggregate 2 X 50mm pipes into the 63mm ports on the pump) it leaves me without two return jets.

I have a small jet (fed with 50mm pipe) on the stairs. And a 25mm return for the Polaris.

I do have a large (100mm side port on the pool which floods a reservoir that has a 50mm outlet. This I have been trying to use as a suction but unsuccessfully. That reservoir is also connected to the main drain.

What's the thinking on using that reservoir and the big side port as one of the returns? There will be no 'jets' to move the water around (except on the stairs) but there will be a low pressure continual return.

Answers on a postcard please!

(Thanks in advance)

Justin

 

[cowboycasey]

Justin,

Is there any way to change out the skimmer and add return lines, I suppose not or you would have already done that... You may have to go talk to the company who installed the pool and see if it can be retrofitted...

Can you re purpose the Polaris booster pump and use that as 2 returns? that would serve you better and cheaper as they really do not work all that well anyway.. Robots are way better and more efficient now...

Other than that I am really not sure what you could do...

 

[Jpadie]

Hi

The Polaris 280 line is only 25mm but it is already a return in the sense that whether or not the Polaris is plugged in there is water coming out.

I think the idea of pushing water back into the reservoir for feeding the pool via the side port works in principle. But there won't be any good 'jet' towards the bottom to create circulation. Not sure what I can do about that...

So,. Yes it's possible to replace the skimmer units on a magiline pool. But they are monoblocks that are inherent to the structure of the pool. I'd need to dig them out (concrete deck) drill out the concrete in the wall cavity and replace it. I fear it is not that practical.

What may be more credible is to dig out the concrete down to 1m20 or so and put a hole in the skimmer surround and plumb it into the pump. Then relay the concrete after pressure testing the joints. It might also be possible to make a shallower dig and plumb higher into the skimmer. I think not though as the skimmer surrounds are shaped like a square wave down their profile.

There is also the hint of a built in port at the bottom of the skimmer. Perhaps this could be used. Unfortunately I cannot find any photos of the version of the filter from 2005. They changed structure in 2006. So I could find that I've dug out the whole caboodle and there isn't in fact any port I can access!

 

[Jpadie]

Attached a schematic of the skimmer

 

[Jpadie]

i have just had communication from the manufacturer. They have not answered the question of whether it is possible to retrofit a classic filtration system; but they have sent me the original installation manual.

the useful pages are below:

This is the overview of the pool showing the hydraulic connections. it's almost identical to mine, save that I have a return jet on the steps and I now have a separate return jet to the polaris vacuum.



And this one shows a face view of the monoblocs.



the bit that's interesting (potentially) is the nub at the bottom right in the second image from the bottom right. There's a wee spur that looks promising. and at the bottom left of the images you can see a very similar profile and a connection into that spur. although this is for a SGB402 rather than an SGB401. I think that the difference is the 402 also has a flat area at the side half way up the skimmer that could be used for a port.

I have one 402 which is currently the main suction point (and I'm planning to use as a return).

It almost convinces me that it's worth digging out the concrete now. I may be able to retain the exiting jets as returns and still get access to the suction lines. I'd need to find a way to block off the link between the skimmer and the jet but that should be feasible, shouldn't it?

 

[cowboycasey]

I have never seen anything like this and now understand why your are trying to change it.. A regular skimmer and return is so much better and easier...

I have no idea if you can block it off but once you get in there you should be able to do something... If you do cut it all out and change everything I think you may be better off but that is way over my head...