macgd016

All is now clear, thank you so much!!

Thanks. You are quite right when I wrote "However, you have answered one point that has puzzled me for years and this is why with such high CYA levels people do not suffer from permanently green pools, whereas in practice most people who only use their pools themselves, just two people who take a dip once or twice a day, rarely have an algae problem but those who let their houses out, families who are in the pool for eight or more hours a day, get a green pool once a season. I think it is because we are very lucky in that our water is from mountain springs and there is no significant agriculture for a hundred miles or more, when I tested some years ago for phosphates and nitrates I could not get a reading at all. So thanks for clearing that one up for me." I was referring to local experience. However, I am sorry but I'm still a bit confused as to what you are saying about CYA/FC. I normally use www.poolcalculator.com which shows that with CYA at 0 the recommended FC is 1 -3 ppm and 10 ppm shock. With CYA=50ppm FC=4-8 and Shock 16ppm. This is also where I originally got figures for CYA=400 FC=30-43ppm. Reading your comments on another forum, your chart http://troublefreepool.com/~richardfalk/pool/HOCl.htmand http://www.troublefreepool.com/threads/2177-Chlorine-CYA-Chart it would appear that an easy guide to FC is to aim for FC=CYA*11.5% with a minium FC=CYA*7.5% and FC=CYA*40% for shock, unless I'm demonstrating that I still dont understand the CYA FC relationship!!!!!!!

Once again many thanks for your reply, but oh dear you have just blown my limited understanding of the CYA/FC relationship and with it the level of FC I need in my own pool! I have always used the poolcalculator.com calculator which tells me that with CYA at 400ppm 40ppm of FC are needed, I had assumed (by the sounds of it wrongly!) that this would give me an equivalent (CYA=0) FC or 1 – 3 ppm. For my own pool the CYA is 50ppm and I try to keep the FC above 5ppm but from what you say this is only giving me equivalent FC of 0.1ppm. Is this correct or am I totally muddled? However, you have answered one point that has puzzled me for years and this is why with such high CYA levels people do not suffer from permanently green pools, whereas in practice most people who only use their pools themselves, just two people who take a dip once or twice a day, rarely have an algae problem but those who let their houses out, families who are in the pool for eight or more hours a day, get a green pool once a season. I think it is because we are very lucky in that our water is from mountain springs and there is no significant agriculture for a hundred miles or more, when I tested some years ago for phosphates and nitrates I could not get a reading at all. So thanks for clearing that one up for me.

I have converted to liquid chlorine but I know a good number of people who still use chlorine pucks and I have a quick question. Given that many of their pools will have CYA above 400ppm is it safe to swim in them if the FC is kept at the recommended 30 – 45ppm. I recognise that with CYA at this level the chlorine is effectively only 5ppm but is this still true in terms of its detrimental effect on skin, swimming costumes or if taken orally.

I have a pool at my holiday house and I wonder how practical it might be to keep the pool closed and covered through to June. I suspect this has a lot to do with water temp so its worth saying that by June the pool will normaly be in the 20C's.

Ah, Just been reading up on this and it seems it creates Chlorine Gas, so I guess you shouldnt do this unless you are in a war zone and even then you will get done for crimes against humanity, that will be a no no then!! Shame it looked like a neat solution for a few seconds!

I'm sure you shouldn’t/can't do this BUT.....is it feasible to add muriatic acid to liquid chlorine? I only ask as I regularly need to reduce my pH so if I could work out the dosing I could add muriatic acid to my chlorine and pump it at the same time. Not only would this help me keep my pH stable but it would reduce the calcification on my injector.

Forgive me it is CH I'm measuring, I have a Lamotte 7022 as we cant get the Taylor kits in Europe, which means my CSI is fine. I hadn’t thought of using a venturi injector as these are primarily designed to 'suck' fluids but I guess it should work with a solenoid metering pump. The plumbing would be a challenge in the confined space I have though, particularly if I need to have a flow control valve to divert flow through the venturi. The other issue is that this will add new potential points of failure within the plumbing which, as I am not always in residence, I would like to avoid if possible.

I am using a Prominent Beta solinoid pump. The CSI is normally OK, I try to keep the pH at 7.4 but it tends to raise but is kept below 7.8 at all times. TA is normally reads 80 but is lower than this allowing for CYA which is 60, however, TH is about 400 which is higher that I would like but think I am stuck with it really. The 'scale' is very white and very soft which is why I wondered if it is salt. The injector is just a none return valve so dosent stick out into the water flow very well so I am wondering if I might be better finding something with some form of pipe on it that will stick out into the center of my 50mm supply pipe.

I have an automatic liquid chlorine system on my pool. This works well most of the time but I am finding that the chlorine injector is getting a scale deposit of some sort, perhaps salt?, which stops it working. This used to be just an annual problem which was manageable but now seems to be happening more regularly. Any thoughts on how to stop this happening?

Thank you once again for your valuable advice, I will print this off and give it to my friend, hopefully this will give him the guidance he needs

Come on guy's, someone must have come across an article that explains that sun cream acts as a catalyst for algae growth and that filtration and shocking is needed to resolve it, or have I got it all wrong?

I have a problem in that my good friend manages my pool for me whilst the house is rented out. He is a lovely man who is very dilligent and works hard but at some point most summers the pool goes a little bit cloudy and despite being shocked then goes green. I have explained many times that when this happens he needs to shock the pool and then keep the chlorine above 10 ppm until it is nice and clean again. The CYA is around 30 ppm and I have an automatic liquid chlorine pump so shocking and keeping the chlorine level high is very easy. HOWEVER, my pool manager (friend) insists that there is no algae in the pool and that it is just that the renters are using too much sun cream and therefore the pool needs flocking. Is there an article somewhere that I can send him that explains the procedure for clearing a milky/green pool as I seem unable to persuade him that the above is the right way to do it.

If the range between colour change was only one or two drops I wouldn't have an issue but when testing the CH the range between the colour starting to change and fully changed is 400 to 600ppm

I don't think you will be disappointed, I have just been out to my house in Spain for three weeks and used the test kit every day, more out of interest than out of necessity though. It is so very much easier to read than test strips or OTO, this for me makes it worth the expense for this alone. My only criticism of it is that it does not read high chlorine levels well and that there is nothing in the documentation to alert you to this. Other than this it is a fantastic bit of kit. The FC test gives an unequivocal reading as the pink changes to clear dramatically as the last drop is added, pH is really easy to read using the Comparator slide, the ALK test gives a rapid change from green to red within one drop so the reading is clear. The only test that is slightly unclear is Calcium Hardness, in my case the CH is over 400 and I am not sure whether I should stop adding drops as soon as the colour starts to change to blue or when it has fully changed. Using the 7022 daily has taught me at least one valuable lesson though, you need to take your FC reading at the same time each day as FC varies during the day, in my case by as much as 3ppm.