Water Test Results

[robquick]

Hi,

I've just purchased a Lovibond photometer and would appreciate some advice on the results.

FC - 4.86

CC - 2.12

PH - 7.81

CYA - 89

TA - 54

Calcium - 160

I've shocked the tub to 25ppm 3 days ago, does the CC seem very high having just shocked ?

What else can I do to bring the CC down?

Is my CYA too high, I used Dichlor for about 2 weeks then switched to Calcium Hypochlorite about 4 weeks ago?

My PH keeps rising to around 7.8, what's the best way to stabilise the PH?

I would like to switch to bleach however, I worry it will damage the tub in some way, should I be concerned ?

Cheers.

[chem geek]

If you measure the CC soon after a soak, it will be high, but it's temporary. You should measure the CC just before your soak. It's unusual for it to truly be that high if enough chlorine has been used so I suspect the numbers. Most people that are using the Taylor K-2006 FAS-DPD chlorine test kit don't measure such high CC values. Do you smell a chlorine smell that isn't a faint bleach smell but smells more like an improperly managed pool?

Calcium hypochlorite will increase the Calcium Hardness level so could lead to scaling if you keep using it. As for stabilizing pH, you've already got your TA low so you need some sort of pH buffer. We normally recommend 50 ppm borates (usually from boric acid), but you may not be able to get that in Europe. You could use a phosphate buffer, but with your added calcium it'll precipitate a lot, make the water cloudy, and clog up the filter.

Bleach is fine to use IF you build up CYA in the water first. If you've cumulatively added 33-44 ppm FC of Dichlor, then you should have 30-40 ppm CYA which should be fine for using bleach.

[robquick]

Thanks.

Should I be concerned with my CYA being do high ?

[chem geek]

89 ppm CYA isn't ideal, but it's not a disaster either (30-40 ppm would be more preferable). Just don't use any more stabilized chlorine. And yes, the higher CYA will make the active chlorine level lower at the same FC level and when it gets very high as from continued Dichlor-only use it can cause one to get behind oxidizing bather waste and can have CC rise, but I don't think that's the case in your situation since you did shock to a higher FC.