Few questions about my new (used) spa

[wes8398]

We just hooked up and started running our new (to us) spa that we purchased. I went with the Bromine system that's laid out in the sticky here, and over the first few days everything seems to be running perfectly. I'm inclined to think that I should probably do a full decontamination since we bought the tub used (a year old), and it also sat in our back yard for 2 months while I prepared the deck and a pad for it to rest permanently, but there doesn't seem to be any chlorine/sanitizer demand so I think that can wait until my first drain and refill.

One of my questions is regarding the use of the TF-100 kit to test my Bromine spa. When I do the FAS/DPD test, is that testing chlorine, bomine, or just general sanitizer (IE hypobromus acid)? Is it testing "free", or "combined"? Also, does the reagent test for combined sanitizer still work?

Anothere set of questions is regarding my spa's alkalinity. I tested it yesterday to be about 50, which would be very low for my pool (also running BBB method), but seems to be acceptable for spas. My worry with this is that an ALK level of 50 wouldn't 'buffer' pH as well as a higher level would, so do I actually want the level this low?

And finally, I encountered my first pH issue with the tub yesterday. I got home from work in the morning and took these readings with my TF-100:
FC: 3
CC: 1 (thinking this is from MPS that was used on first fill about 3 days ago)
pH: 7.8
TA: 50
temp: 99*

I added just under 100 ml of 12.5% chlorine in order to 'shock', and then left it for the day while I slept. When I got up 7 hours later, I tested the water again. These were the readings:
FC - 5.5
CC - 1
pH - 8.? - it wasn't really purple, but definitely over 8
TA: 50
temp: 99*

Now the 100 ml of 12.5% should have brought my sanitizer up to at least 10, but it didn't seem to do so. I also know the chlorine would bring pH up a bit, but that much seem concerning, which brings me back to my previous statement about the TA being so low.

So, after these tests last night, I put the bromine puck floater back into the tub (I had taken it out for the previous 24 hours in hopes to make it easier to find any chlorine demand), and put about 3 teaspoons of Borax into it to hopefully bring the pH back down. I'll be back home to test it again in a few hours, so I'll post back with those numbers when I wake up this afternoon.


Oh, one other beef I have which is with the pool calculator ... why are all these powders suggested in grams rather than tea/table spoons? I don't have anything around the house to measure out grams easily, so I keep having to look up how many grams of X (ie: MPS) is in a teaspoon or tablespoon, then convert it. Blah!

Any comments/suggestions would be greatly appreciated. Thanks!

 

[wes8398]

Well, in proof reading my previous post I've just realized a stupid mistake. I accidentally put borax in the water to LOWER the pH. Oops.

So this mornings readings were (remember, I put the bromine floater back in 13 hours ago):
FC - 8
CC - 1.5 (mps?)
pH - 8.?
TA - 50

 

[Bama Rambler]

I'm sure you already know but you need to get that pH down first.

MPS will show up as CC's so don't worry about that too much.

 

[wes8398]

When I got up today, I put a few teaspoons of dry acid in the tub and let it circulate for a bit. Tested again, and pH was down to about 7.6. I thought that since I was messing with the pH and TA anyway, I might as well add the Borates that I wanted to try (via 7 Mule Team borax). So, I added about a cup and a half of the Borax (should get me ~30ppm borates) along with a few more teaspoons of dry acid and let it circulate again. I tested a few hours later and pH and TA were up, both from the addition of the Borax I'm assuming. Numbers were:
FC - 9
CC - 1.5
TA - 70
pH - 8.2
CH - TF-100 was washing out I think. I got pink water, but 50 drops of the next stuff still didn't turn the sample blue.
Temp - 98*

Using the pool calculator (and a bunch of messy conversion from ounces to teaspoons) this time, I added 14 teaspoons (2 oz, 3 tsp) of dry acid to bring the pH back down to a reasonable level. It's currently circulating and I'll probably test again in an hour or so.

 

[wes8398]

Update (if anyone's watching):
After letting the tub circulate for a few hours, I tested again and pH was down to 7.2. Although TC was around 10, I still couldn't resist to jump in for a 45 minute soak while the lightening storm passed over. I just got out, and WOW do those borates ever make a wonderful difference in the feel of the water! My skin feels all silky and smooth even after getting out. Our first few soaks, I think my wife and I both got out of the tub feeling a little dry because we both raced for the hand lotion when we got back inside. lol

So is it possible that the high sanitizer levels washed out my CH test earlier? Or is it because I'm using bromine as a sanitizer? Or maybe my test chemicals have bit the dust...?

 

[Bama Rambler]

Some metals will interfere with the CH test. You can look at the extended test kit directions sticky in testing area and it may help.

 

[wes8398]

As far as I know, my water doesn't have any metals in it...

 

[Bama Rambler]

You can try the fading endpoint remedy and see if that helps though.

 

[wes8398]

Well I tested my POOL's CH today and the test worked fine, so it's not my test kit that's the issue. Regardless, both the pool and the spa were filled with the same water, so CH will be the same in both anyway.