When to add Borax - new spa, first fill

[J24]

I filled our new 355 gallon spa and balanced the water to these readings:

78 degrees (still heating)
CH = 190 (up from the tap water of 20)
TA = 50 (up from the tap water of 30)
ph = 7.6 (down from the tap water of 8+)
FC = 8 (calculated after adding dichlor)
CYA = 7.6 (calculated after adding dichlor)

I would like to get the Borates to 50ppm but I don't want to drive up Ph and TA -- or is this inevitable and I'll have to bring it back down with dry acid?

Planning to use dichlor/bleach and using the Pool Calculator. Using a Taylor 2006 test kit.

Thanks.

 

[PaulR]

Welcome, always nice to see another spa owner show up!

The pH might drift a little as the water heats up, I'd wait until you were at normal operating temp before doing borates. You want the TA and pH right where you want them before you do it.

There's a description here describing how you can add borax and acid simultaneously to maintain a steady pH. Also you can use the Pool Calculator which will figure amounts for you.

I use borates in my tub, the small amounts needed require being a little finicky but as long as you're reasonably careful you won't go too far wrong.

Let us know how it works out!
--paulr

 

[J24]

After 2 days of tinkering and soaking, here is where I stand -- comments and suggestions appreciated

Temp = 102
FC = 10+ (big shock after family soak)
CH = 190
TA = 50
Ph = 7.5
Borates = 40 (calculated)
CYA = 26 (calculated)
CSI = -.31 (from TPC)

Water looks, smells and feels perfect.

I am switching to bleach going forward
I could tweak the CH and use Borax to move the ph up and get closer to a neutral CSI, or I could call it good for now.

355 gal tub
Taylor 2006 kit
BBB method

 

[chem geek]

I'd call it good. One thing to note -- use Dichlor for 1-2 days once a month to keep the CYA constant. The CYA drops around 5 ppm per month in hot spas (it gets oxidized by chlorine) so you'll want to add 5-6 ppm FC of Dichlor every month with the rest of the time using bleach (other than the first week or so building up the CYA level after a fresh refill). This is a new twist with the Dichlor-then-bleach method now that we've got enough people on it to get some reasonable measurements (as seen in this thread).

In the future, when adding borates to spa water, you can use products such as Gentle Spa which are mostly boric acid, though they are more expensive then getting boric acid directly or using 20 Mule Team Borax plus acid. However, the quantity is small and you'll probably go 6 months before changing the water -- up to you.

 

[J24]

Great advice and that totally makes sense. I can just test the CYA once per month to determine when to use a little dichlor.

On the GentleSpa -- I tried three different pool/spa stores around town and couldn't find anyone who had it. I presume online is the way to get it. The 20 Mule Team / dry acid worked just as the Pool Calculator predicted.

I can't imagine how lost I would be with my first spa without the advice and experience on this forum.

Thanks to all of you!

 

[PaulR]

Is this a fiberglass tub? A mildly negative CSI should not be a problem. Mine runs about -.2 or so.

The only caveat I would add to chem geek's recommendation is that with a brand-new tub, you probably do want to change the water early the first time around, say after a month. There are inevitably some manufacturing residues in a new tub and you want to clean that out relatively soon.
--paulr

 

[J24]

Thanks. It is a new tub. Hadn't thought about an early water change but that makes sense.

Any reason I can't use the water on the lawn and shrubs?

 

[PaulR]

I remember reading one report that water with borates seemed to "burn" some more delicate vegetation. But in general, as long as you haven't been using any "mineral" systems or metal-based algaecides, I think it should be okay. In fact there was at least one pool owner doing water replacement by using the pool water for irrigation and using the irrigation allowance to refill the pool!
--paulr

 

[chem geek]

Thanks Paul for the very important reminder about early water replacement after the first fill for a new tub.

As for checking the CYA once a month, that is probably overkill, especially with how slowly the CYA drops. You could probably just check it after 3 months to see how the monthly additions of Dichlor have worked to keep the CYA stable and then adjust accordingly if needed. Of course, when one first gets that wonderful test kit, one just can't help oneself from testing and testing...

 

[J24]

LOL! Testing, testing, testing. This is so true. My kids love it as well so I have made them the official water testers. We created a simple spreadsheet to log the use, test results and our chemical additions. Hopefully we'll figure out the cause and effect here.