Noob Water Chemistry

[petepuma1]

Hi,

I just hooked up my 350 gal hot tub and used the bromine the dealer gave me. My water readings are off and wanted to make sure I add the right chemicals.

1ppm FC

1.5 Cc

6.8 Ph

35 alk

20 CA

I know I need to build up basically everything, no?

So am I wrong to assume I need to add...

More bromine? Or am I adding bleach to build up the FC?

Mule 20 to build up the alk and ph?

If I'm correct then is 3/4 cup the correct dose of both?

I think im starting to regret not just doing the Dichlor/bleach method.

Thanks in advance.

[chem geek]

pH Up (soda ash) would increase both pH and TA. If the TA still needs to be raised further when the pH is OK, use baking soda (or pay more for Alkalinity Up at your spa or pool store). By "CA" do you mean "CH" or Calcium Hardness (as opposed to CYA or Cyanuric Acid)?

Are you sure CC is 1.5 ppm? Or is that Total Chlorine so CC is really 0.5 ppm? Are these readings from the dealer or from your own good test kit such as the Taylor K-2006 or for bromine the K-2106 (though you can use the K-2006 for both).

To get to a pH of 7.5 with your numbers you'd add only 0.8 ounces weight or only 1/10th cup of soda ash. That should bring the TA up to around 52 ppm as well. You can then add 1.5 ounces weight (1.2 fluid ounces volume) to get the TA to 70 ppm since I presume using bromine you may be using some net acidic chemicals. There's no way you add 3/4 cup -- where are you getting such quantities?

To preven foaming, you could increase calcium hardness, but you could just wait to see if foaming is a problem in your spa.

Dichlor-then-bleach wouldn't necessarily be any easier on startup given the water parameters you have.

[petepuma1]

Thanks Chemgeek for the reply.

I meant CH (damn auto correct)

I'm not sure if my old test kit was giving me inaccurate readings after spending the winter in a storage bin, so I bought a new one.

I've done some adjustments and here are my numbers from the new Taylor2006 test kit.

CH 110ppm

Alk 65ppm

Ph. 8.2

FC. 6

Not sure how to get my TA up and at the same time the ph down? My mistake was adding too much baking soda to raise the original ph from 6.5. When I called Taylor they said I needed 3/4 cup of baking soda. I added 1/2 cup to play it safe and I was still way over. Leson learned. Almost inclined to drain and start over now that I have the sodium bromide for start up.

[petepuma1]

Screw it, it's about a month old so it's due for a water change. I'll start draining it.

[chem geek]

For spas, unless you are using net acidic chemicals, you want your TA lower to have less carbon dioxide outgassing that causes pH rise. To provide additional pH buffering given the lower TA (down to 50 ppm if necessary), you can add 50 ppm Borates most easily added from boric acid from Duda Diesel or The Chemistry Store.

[petepuma1]

Ok, so after drain, refill, 12oz calcium booster, 1 3/4 oz of sodium bromide, 1/2 cup bleach, and no aeration.....

PH 7.4

TA 30

CH 140

FC 10.25

Tub is 375 gal with ozonator. Those numbers looked good to me, we'll everything except the TA and waiting for the FC to drop a little. Or is the TA ok considering I have the PH so perfect? Thanks again Chem Geek for helping out.

[petepuma1]

Water tested at

FC 6.75

TA 20

Ch 120

Ph 7.2

Should I add some baking soda to raise the TA? And if so how do I get the ph down afterwards.

[chem geek]

Yes, adding baking soda will raise the TA. It may also raise the pH some but not too much. To lower the pH you can add acid and that also lowers the TA but not by very much.

You basically want to get your TA to a level where the pH tends to be stable given the amount of aeration/usage of your spa.

[supermanotorious]

I was chatting with a trusted local pool supply about hot tub chemicals and we came to the conclusion that relying on the ozone generator, draining and refilling several times a year will cost less than buying chemicals. My water has done fine using this method. If the water starts to get a little dim, I add what I call, a "crack rock" of chlorine and this usually brightens it right up until the next drain / refill.

[petepuma1]

So if my PH is stable with a TA of 30ppm should I just leave it alone?

[chem geek]

30 ppm doesn't give you much room if for some reason something acidic is added to the water. 50 ppm would be better. If you use 50 ppm borates then the rate of pH rise should be slow or not noticeable even with 50 ppm TA.

[petepuma1]

Ok, cool beans. And this can be done with Mule 20, correct? Also, how much should I add to a 375 gal tub? And how do I test to know I'm at 50ppm on the borates? Thanks Chem geek.

[RaviePoolGirl]

Here is a link to the pool calculator that you may find very useful.

http://www.troublefreepool.com/calc.html

Borate test strips

http://www.amazon.com/Lamotte-Insta-Test-Borate-Strips/dp/B004KZNPL2

Here are instructions on how to add borates, but NOTE, they are for a pool. Use this info to get a general idea of how to do this.

http://www.troublefreepool.com/threads/90257-Borates-Why-and-How

[petepuma1]

Thanks for the reply.