Jump to content

Ta, Ph, Ch, And Borate Questions


Recommended Posts

Hello all.

Thanks for all the fantastic info on this forum. I've learned so much. I just bought my first spa, 500 gal Artesian Island and love it. Had it for 2 weeks and am researching chemistry and sanitation like a mad man to the point of obsession. The spa has an ozonater and the dealer set me up with an initial Spa Frog system. I've got 1 unused bromine cartridge and once it is done I'm dumping the Frog for bromine tabs in a floater (I've researche the 3 partbromine set up system). We have heavy use with teenage kids and friends and the low level of bromine was not keeping up with the bio load. With all the dichlor/bleach additions it makes no sense to spend the money on the Frog IMO. I initially was shocking with MPS and swithched to dichlor. After learning about the CYA I've swithched to bleach since the CYA levels should be more then sufficient now..

I have a good understanding of basic chem and the relationship between TA and pH as I also have a reef aquarium. I understand that borate helps buffer the pH by keeping the alk from dropping. I currently have the following parameters

pH 8

TA 90

CH 250

I've got a Taylor K2106 ordered and have been using my neighbors pool test kit . Here are my concerns.

1-Pool calculator states TA should be 50-80. Manufacturer states TA should be 80-140. Is low TA going to affect the spa in any hardware way physically, or only the pH buffering? I have not added boric acid yet until I get the TA proper.

2- Adding boric acid should increase the TA without affecting pH, thereby increasing the buffering capacity, correct? If so I can see why lowering to 50 is ok as the borate will increase TA back up near manufacture's recommended.

3- In order to maintain a sufficient Calcium level TA needs to be at a certain level to be balanced (at least it does in my aquarium) and stop the precipitation of calcium carbonate. Given my Ca level do I need to worry about Ca falling out of solution if I drop the TA further?

4- Once TA is balanced how much borate do I add? I assume there is not much borate in city water. I will be using 20 Mule and muriatic acid.

Thanks for any help and suggestions.

Link to comment
Share on other sites

4- Once TA is balanced how much borate do I add? I assume there is not much borate in city water. I will be using 20 Mule and muriatic acid.

You want to end up with 50ppm borates. Here's procedure I use

Go to the Pool Calculator and enter the water volume for your spa

enter 50 in the borates "Target" field

The calulator will give you the amount of Borax and acid (Example for 350 gal 21oz. Borax & 9.8oz Muriatic Acid)

Get a large clean bucket ( I use a Home Depot 17L) fill it at least half way with "Balanced" spa water

Accurately measure 1/2 the required Borax (10.5oz by the example) and add to the bucket

Mix well

Measure 1/2 the required acid (4.9 oz.by the example) slowly add the acid to the bucket. (Wear Safety Glasses and do not place your face directly above the bucket. There will be an off gass reaction)

Mix well

Repeat with remaining Borax and Acid

Mix well and let stand for 1 hr.

Start Spa pump and slowly empty bucket into the spa

Wait about an hour then check pH. If done corectly there should be little or no change to the spa pH.

Now you have 50ppm borates

Don't forget to enter this in the Pool Calculator whenever you want to calculate any changes

Link to comment
Share on other sites

So long as you don't drink the spa water, you'll be fine. Borates are not absorbed through the skin (see this paper). The 50 ppm limit by the EPA (which allowed 80 ppm in biguanide pools) assumes drinking small amounts of pool or spa water every day and has a margin of safety factor of 100. Read Are Borates Safe? if you want more detailed info. Basically, boron is in food so your body can handle and remove a certain amount of boron each day.

Link to comment
Share on other sites

(85-50)/85 = 41% so 163 gallons, but personally I wouldn't bother and would just get it closer to 50 ppm the next time you do a drain/refill. Seriously, 85 ppm is not a problem. Male dogs showed no adverse effects at 8.8 mg/kg/day (male dogs showed smaller testicles at 29 mg/kg/day after many months of drinking water) so the no symptom limit for a 60 kg (132 pounds) person would be 528 mg or drinking 6.2 liters of 85 ppm boron water every day for months. The EPA has a factor of 100 margin of exposure safety factor so that translates to 62 ml or 2 fluid ounces. You aren't drinking spa water so I wouldn't worry about it. The borates are also not volatile so you aren't breathing it either (and even as an aerosol, the quantities would be very low).

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...