Just Tested Water I Will Use To Fill Hot Tub, quick question...

[mjdieth]

Hi All, I have been lurking here for a while now, ever since I have had my hot tub on order. I am going to use the Dichlor/Bleach method. Although I will have a 24 hour circ pump and ozone, I plan to use the tub every day or two so I think I will be able to manage the dosing. I do not have the tub yet but have just received my Taylor test kit to test the water I will be using (from a hose outdoors) to fill the tub. Here is what it tested out as:

PH: 7.4
TA: 50
CA: 90

This looks absolutely perfect to me right out of the hose, which makes me skeptical. Will there be any affect of adding the dichlor right to this once the tub is filled, I mean, what will happen to these readings once I add it?

Thanks for any information you can provide, this site is wonderful!!

 

[Arobbert]

Those numbers should stay the same. You might want to test the tub when filled to be sure.

Also be sure to perform a flush to clean out the pipes. Often there is material left from the manufacturing process.

 

[ant 83]

Certified Pool Operator (CPO) training -- What is not taught

For every 10 ppm FC added by Dichlor, it also increases CYA by 9.1 ppm and decreases TA by 3.5 ppm.

So, roughly, for every 30ppm fc added with dichlor, alk drops 10 points.

At 50 TA, you are already on the low side.

I recommend increasing your TA by at least 20ppm right away. Increase more depending on your CYA target you wish to use. You can add some 20 mule team borax if you wish. Use pool math to calculate amounts to add.

edit to add, increase TA with either soda ash, or baking soda. The borates are in addition, and are optional.

Also, always test ph BEFORE you aerate/soak/add bleach, not after.

 

[mjdieth]

Certified Pool Operator (CPO) training -- What is not taught




So, roughly, for every 30ppm fc added with dichlor, alk drops 10 points.

At 50 TA, you are already on the low side.

I recommend increasing your TA by at least 20ppm right away. Increase more depending on your CYA target you wish to use. You can add some 20 mule team borax if you wish. Use pool math to calculate amounts to add.

My PH is actually a bit low, so it looks like adding about 2oz of baking soda will raise TA about 20 points and PH just a bit too, perfect and easy scenario I guess. I think I got pretty lucky with my fill water here.

 

[ant 83]

yup. my fill water is 50 ta as well. It works nice. I still have to buffer the water a bit after fresh fill, to counteract the acidic dichlor.

ph of 7.4 is a good place to be. Make sure you test it when it's at its lowest point. IE: after the tub has been covered for at least 8 hours.