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[tollgate]

My pool was completed on 31st December last year. For the next three months my pool was looked after by a "pool guy" and this was included in the pool price. Since April I have been doing my own pool maintenance.

I have a question about test kits. Up until now I have been using a dropper kit and this was giving me pH 7.2 and Total Chlorine of 3.0. I recently purchased an Aquachek strip test kit and it gives me pH7 and free chlorine of 1.0.

So which is more reliable?

The Aquachek kit also tests for total alkalinity and stabiliser which is quite handy.

[curtklay]

The Aquacheck strips are good as long as you can compare the colors to the standards accurately. It takes a little getting used to. The alkalinity test is crucial. Also keep in mind that total chlorine and free chlorine may not be the same. When the total chlorine is higher than than the free chlorine, you are due for shocking or super chlorinating.

[tollgate]

Thanks for your comment on test kits. Now shocking was going to be one of my next questions. When I took over maintenance of my pool I did quite a bit of research on the subject. Shocking was mentioned a lot with different web sites suggesting a shock once a week, once a month or just "when needed"

I asked the guy who constucted my pool. He said "no need to shock". So my pool hadn't been shocked for almost 5 months. But over the last few days my free chlorine has fallen to around 0.2ppm and I haven't been able to raise it much. I use chlorine tablets in a floater. Usually one is enough, but I now have three in there and I'm still struggling with free chlorine.

Today I purchased some sodium hydrochloride liquid and have shocked the pool with 6 litres which I think will be enough (my pool is approx 43000 litres). I guess tomorrow morning I will find out if it has worked.

I would be interested to hear other pool owners comments on shocking.

[curtklay]

Shocking should be done every week or two. 6 liters of liquid chlorine should do it. Whenever your total chlorine reads higher than free chlorine, you are due for shocking. When the chlorine levels come back down to normal levels, check your PH and alkalinity. Adjust if needed doing alkalinity first. When you raise alkalinity, odds are the PH will rise with it. Use sodium bicarb to raise alkalinity. Use soda ash to raise PH.

Normal maintenance consists of regular shocks, and alkalinity increases at least once a month.

[tollgate]

Well shocking the pool certainly had the desired effect and my free Chlorine is now 3ppm  - if anything a little on the high side. I've closed some of the slats on my floater to help it drop a bit.

My pool only has light usage - probably about 7 man hours per week. But it's an outdoor pool so the water is always warm - around 30C. I think I will shock every couple of weeks. pH is 7.2 and alkalinity 50 ppm. Do you think I need to raise the alkalinity?

[curtklay]

Yes, your alkalinity should be 80-100ppm. For your size pool, add about 8 pounds of sodium bicarb
  (baking soda) sprinkled around the pool. This should also nudge your PH up to the ideal range of 7.4 to 7.6. Check weekly, and keep it up there. It tends to drop naturally, and if you add acid to the pool to lower the PH, alkalinity will drop with it. It can get to be a roller coaster when things get out of balance.

Your shock treatment worked fine. The chlorine level will drop when the liquid chlorine burns off. Keep your floater adjusted to maintain 1.5ppm. Also remember that chlorine tablets are acidic, and will cause your alkalinity to drop. The upside is they usually keep the PH in the ideal range.

My advice is check and adjust alkalinity weekly. Shock every other week. Conditioner and hardness really only need to check once or twice a year. Enjoy your pool!

P.S. I worked in the pool industry in California for 25 years.