I'm new here but I did go to pool school and I have learned a lot. Still I have some questions First of all, I am from the Netherlands and thus have access to different chemicals, different tools and I am used to a different metric system. Also, not a lot of people have a pool in the Netherlands, since it rains 360 days a year Kidding but with luck we have 2/3 months in which we can use the pool on good days. This means that there is not a lot of information to find on problems which are a bit more difficult to defeat, other than: alkalinity is low or high, ph is low or high etc.
Especially not on the problem we encounterd. That is what I found here and this website + very good local pool dealer saved me from simply draining the **** pool.
Last year we bought a house and it had a pool, fulfilling a dream 10yrs earlier than expected. We had no clue what to do with the pool and let the company who installed it advise us. He advised us to keep it closed, make sure it was heated when the temp was below 0 celcius and leave it alone. Mistake 1. He also helped us start the pool back up, measuring was not needed he said. Mistake 2. Of course the water was a dark shade of green. He seemed to know by heart that the PH needed a rise and advised us to add a chlorine shock. Which did not work, plus I did not measure any chlorine with a simple DPD test the previous owner left behind.
So I went in and read all I could on the internet regarding pools (which I should have done in the first place) and purchased a test kit. We do not have the advanced test kits like you guys have. At least, not being a pool specialist, you don't. Other digital tests we do have are expensive and limited to FC, CC, Alk and PH. I might pick one up while I'm in the US in a few months. So I did a test with a strip and PH was ok but Alkalinity was only 40, CYA 30/40. No chlorine.
I bought TA+, got the TA up to at least 120ppm. I tried another shock, didn't work either and no reading again, not even after 30 minutes. I did this a few times, with different types of dichlor. (I began to think that he sold be washing powder which just smelled like chlorine). My teststrip did read chlorine after swiping the bucket I used to divide it over the water so I was sure it wasn't bleached by the chlorine.
So, a lot of euro's wasted, no chlorine reading and still a green pool. I drained 1/3 of water from the pool, shocked it, used anti-algue gel (I'm not sure you are familair with this but it gives you a small layer on the sand filter and it consumes fosfates) and I added tabs which bind the small debris (don't know how you call it). The gel catches the debris on the filter and after you had enough, you simply backwash. That at least got me a somewhat clear but still green pool. No clorine reading.
I started searching on English websites and found this one. Plus some topics from people with the same problem as I did. This was very interesting: http://www.troublefreepool.com/conte...tain-shockingl Though I have the handicap of not having a good test kit, I decided to try this. I got 25 liters of liquid chlorine, 13,8 percent and used 6 liters this morning. Which should have been enough for 20ppm. First time I got a purple test reading after an hour I continued testing with the strips which only go till 10ppm. I decided that when it would drop, I would add another 3 liters. After 6 hours, my pool was clear! Gone was the green water and crystal clear water appeared. I was (and am) ecstatic.
So, this evening, about 9hrs after the shock, I saw that the chlorine reading drop under the 10 but above 5. The sun was on the pool most of the day so I can imagine that it burned off some of the chlorine. I cannot use the cover at the moment as it would discolor from the chlorine level.
I took pictures after every test, so I could follow the discoloring of the strip somewhat better. I realize it is still guesswork but hey, a woman can try and at least, now it's clear. So after seeing it drop, I added another 3 liters and brought it back above 10ppm again.
First I want to thank you for providing the info. Otherwise my morning would have existed of draining the pool and the next few days of filling it. I hope to get there with the limited tests I can do at the moment. The new company I have found to help me with my pool is too far away to have it tested every day.
So that is a lot of background information but after reading previous topics I kind of have the idea of the suggestions you would give me so you need to know what I did already and why I don't have a good test kit.
I do have some questions. The slam guide says that I am done when I have a clear pool and my chlorine level does not drop with more that 1ppm overnight. But isn't liquid chlorine supposed to drop fast (in a few days) after shocking? I mean, I always understood that I should have about 2ppm reading for normal pool use and after shocking the ppm should drop within a few days back to normal because you use a fast working chlorine.
So it would be natural to have it drop a few ppm in a day right?
Next, how can I best prevent this next summer?
By the way, the pool is 8metersx4meters, 45.000 liters with a sand filter.