Frank Posted March 11, 2006 Share Posted March 11, 2006 I am a pool novice, Iam considering a 10 x 5 x1.5 metre pool , flat bottomed and have been told that if Iam not connected to the mains drains I cannot have a sand filter which requires regualr backwashing and should therefore opt for a cartridge type filter which does not require backwashing. The pool will be used by gite guests and I believe must therfore comply with DASS norms also. My maximum guest levels when fully open will be 18 persons plus my wife and I .my questions are chlorine or salt sanitization ( preference for the easiest to control and maintain)sand or cartridge type filtrationhow much water does backwash consume how often and can it be run to drain or soak away ( I have a 60 x 30 metre garden area)I don't have mains drainage but have drain off from the roofs which exit the property into the main road outside probably road drains . can I utilise these ???How much should I be looking to pay for a tractor digger to excavate the hole for meThanks in advance for your help Link to comment Share on other sites More sharing options...
Piprob Posted March 13, 2006 Share Posted March 13, 2006 Its pretty much a matter of choice. I chose chlorine because I decided it would be easier to close down and re-open either side of winter. We have a sand filter. You can see through the perspex filter housing when a back wash is necessary. I run back-wash for anything between 20 and 40 seconds depending on how long it takes the water to run clear. I need to back-wash at least once a week due to site conditions. After a 40 second burst, the water level in my 8x4 pools has dropped by around 3 cm - a lot!If you have a pool liner and you use chlorine, you must take great care to control the water temperature; too hot for too long (above 28c) and you'll destroy the liner - especially if you leave it covered for several days. One benefit of salt is that it is more benign. But the close-down and open-up operation can (but will not necessarily always) take longer.You may not be permitted to tip your chlorinated water into a surface water drain. You need to check locally. As for the cost of digging a hole - that depends entirely on how long it takes. Soil differs from place to place. You would be well advised to obtain a quote. A guess would be two men for a maximum of two days, assuming a mini-digger, and assuming you intend to leave the arisings on site. Link to comment Share on other sites More sharing options...
Baz Posted March 13, 2006 Share Posted March 13, 2006 Whilst backwashing is requirement of a chlorinated pool, it is worth pointing out that if the French water restrictions are reimposed as in 2005, then replacing the emptied water could cause a major problem. I have a pool in Essex and whilst at present am not effected by Thames Water Board water restriction from next month. However, I am aware that if Anglian Water impose drought restrictions then use of my pool may be very restricted with perhaps closure of the pool to be considered. Let's hope it rains for 2 months!!!Baz Link to comment Share on other sites More sharing options...
Poolguy Posted March 14, 2006 Share Posted March 14, 2006 Jetlag Thanks forthe question.You haveasked a number of interesting questions, many of which will be a perpetualproblem for pool owners here in France. As for theFirst one. You saidthat somebody told you that you couldn’t own a sand filter because you are notconnected to the mains drain? Extraordinary!!! Who was it that told you that..was it the Marie? Normally they will not get involved in those types ofdecisions. They may insist on a separate fosse for the backwash but I have notheard of them getting involved in filtration specification. You should knowthat using a cartouche is not exempt from cleaning. You will be obliged toremove and clean a cartouche once a week using the hose. Its much the same assand filtration as regards the consumption of water. I suggestthat you consider a sand type filter but fill it with a product called ‘AquaCrystal’, which is one of the Zeolites. This will in effect reduce the need tobackwash to once every 2-3 weeks. It also gives you far better filtration thansand, cartouche or even diatomaceous earth. So from a hygiene point of view,you can not only economize on your use of water but you will more than complywith the DDASS norms on filtration. For theproblem of water, thankfully we are now off water restrictions (for the timebeing) and the rivers once again look full and flourishing. However, it wouldbe smart to allow for the possibility of reintroduction of these restrictions.The best provision would be to install rain water storage, which is nearly mandatoryin other parts of the world but a novelty here. If you store even 1 cubicmeter, then it’s better than nothing. However, for a full season top up on a 10x 5, I suggest that a minimum of 10 cubic meters would be suitable. Take carehowever, that water stored in that quantity will not stay fresh for long. Youwill need to circulate, sanitize and filter it the same as the swimming pool.Recently I have been specifying systems where the water storage will make useof the Pool technique systems and be switched in for an hour or so when thepool has been cleaned. Secondquestion on sanitization.The DDASSwill not accept a salt system, there is no Norm for that and they will requireyou to change if you want to be registered. Hence you are obliged to consider achlorine direct system. I recommend that an automatic regulation system wouldbe the best for you, which are in effect removing the problem of marinatingyour pool from your weekly chores as well as keeping a constant and expert eyeon the Pool’s Chlorine and pH levels. With nearly ever other system there iswork to do, testing and dosing. With the Pool controller, there is nothing todo. Your nextquestion how much water is used during a backwash. Well an interrogation of thefigures should reveal the clue. If your pool is 10 x 5 x 1.5 meters, flatbottom than that will be 75 cubic meters of water. To comply with DDASS normyou must circulate that the entire contents of your pool every 3 hours. So yourpump and filter should be specified to provide at least 25 meter cub per hour.So if your back washing for 30 seconds that should be 25,000 litres divided by120 (30 second periods in one hour) and that would mean about 208 liters. Ifyou do that once a week (necessary with sand, - once a day if you want tocomply with the Norm) that would be 5,408 litrs over a 26 week swimming season.As I said before (and in other threads), if you run a Salt/chlorine system youmay not eject this water to the storm water, it must be consigned to anevaporation pond. If you running manual chlorine direct then your better offwith soak away, but if your using Automatic dousing then you can go ahead andput the back wash on your garden as the chlorine levels are so low that no harmwill come of it. If you are using ‘Aqua Crystal’, then this quantity will bedown to 2,600 liters over a 26 week swimming season which is half of the above.An additional benefit is that the water in your pool will be 35 times cleanerthan with sand. That is: sand will give you 35-micron filtration – this is aparticle of dirt you can almost see. Aqua Crystal will give you 1-micronfiltration – this particle that is so small that it includes everything; all ofthe known undesirable pathogens; as well as scrubbing the water for ammonia andphosphates, none of which you want in your water. This is one spectacularresult, - really clean water. I hope thatI have made the distinction adequately between Filtration and Sanitization. If it’snot clear then perhaps I can put it like this. If you can imaginethat the pool is filled with brand new ping pong balls. Over time with thewind, dust and people in the pool, the ping pong balls become black and thereis many other ‘things’ in there with the ping pong balls. Filtration is asystem where all of the stuff which is not ping pong balls gets taken out ofthe pool. Sanitization is a process where the ping pong balls a cleaned whiteagain. Maybe this is an over simplification, but the point needs to be madevery clearly, that EVERY pool, whether, domestic or commercial needs BOTHsystems. And they should be adequate for the size of the pool. This isdefinitely not the place the save money on the pool build, nor is it the placeto add on something later. You should have a good filtration and sanitizationsystem from the beginning. Not to do so puts your health and that of otherswimmers at risk unnecessarily, as these do not cost the earth. Good systemsare affordable, what is in short supply in France it seems to me, is goodadvice. I hope thatthis has been helpful. Andrew Link to comment Share on other sites More sharing options...
Frank Posted March 15, 2006 Author Share Posted March 15, 2006 Thanks Andrew.I suspect it may be a little more costly than I had hoped but the advantages of bein able to re-use the water on the garden is of benefit as is the "really clean water", yhanks again for an informative reply.Probably have many more questions by the time I'm up and running Phil. Link to comment Share on other sites More sharing options...
Poolguy Posted March 22, 2006 Share Posted March 22, 2006 JetlagIf you want to chat about the options to get you problem solved than I am happy to help.PM me with your contact details and we can chat about what to do.If I can help I will.Andrew Link to comment Share on other sites More sharing options...
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