pH will not stop rising in hot tub

[Kgarriott]

Hello everyone, I have been lurking these forums for the last few weeks since we became new hot tub owners. Some of my questions have been answered, but I have been unable to find answers for the biggest problem we are having... keeping our pH down to a normal range.

Background: We have a 250 gallon hot tub with a built in ozone system (allegedly). We are using Bromine.

We received our hot tub approximately 3.5 weeks ago. Of course we filled it right away, to get it up and running fast. Armed with my trusty test strips (I didn't know how inaccurate they were) I promptly tested the water. Our CH was very low. I learned from a local spa store that the water here, Washington State, was very soft. I also found out that the Alk was low, and the pH was extremely high. I bought bunches and bunches of chemicals, and was able to raise the CH and Alk to normal limits. My pH, however, refused to decrease. I would use my pH decreaser (91% Sodium Bisulfate) EVERY day, and it would never stay down no matter how much I used. We used almost whole cans/bottles of different chemicals, and could still not get the water balanced properly. I found information on the forums about how sometimes hot tub's pipes are filled with antifreeze, and can destroy any chance of getting the water balanced. After 1.5 weeks of using massive amounts of chemicals, I begrudgingly drained the hot tub and refilled it.

I bought the Taylor test kit (as recommended) and bought some Gentle Spa. It took a while (again) to be able to get the CH, and Alk to normal levels, but we STILL cannot get the pH to stay in range. I use the decreaser to get it to about 7.6ish, and 2 days later, it's way over 8 again. I'm at my wits end... I'm afraid to use it, and am spending large amounts of money in chemicals.

These are the latest (2 days ago) results...
CH = 150ppm
Alk = 70ish (70-80)
pH = 8+
Bromine = 1ppm

I added the correct amount of Sodium Bisulfate per Taylor's guide (like I always do) and the level decreased to about 7.7. Today, it's well over 8 again. I have been checking these numbers for pH every 2-3 days, and it's always the same. I know my Alk is a little on the lower end of the range, but I'm afraid use the increaser, for fear of making the pH even worse. I have no idea where to go next, I just don't know what to do. I'm hoping some of you veterans can point me in the right direction. It's really taking all the fun out of being a hot tub owner. ;-(

Thank you

 

[kimkats]

I really don't know much about a hot tub BUT know that in a pool the pH will go up from aerating the water.............well what happens in a hot tub?? LOTS of aerating. I don't know what you do about it but will share a link with you that shows you what we use in our pools that can be bought from Walmart or Lowes:

Pool School - Recommended Pool Chemicals

I also have a couple of other links to share about caring for a hot tub:

How do I use Chlorine in my Spa (or pool)?)

How do I use Bromine in my spa (or pool)?)

The white box at the top of this page is our search box. It stays in TFP so it helps narrow down the hits.

I hope this helps some

Kim

 

[pooldv]

Welcome to TFP!

Lower your TA to 50 and add borates to help with pH rise. It is covered very well in this article, How do I use Chlorine in my Spa (or pool)?

 

[ant 83]

gentle spa has borates in it. i found this.

Gentle Spa For Borates... How Much Dosage? - Hot Tub Water Chemistry - Pool and Spa Forum

4 ounces of Boric Acid per 150 gallons would yield 35 ppm. 4 ounces of sodium tetraborate pentahydrate per 150 gallons would yield 30 ppm. This is close enough for anyone to just call it "30 ppm" even if the former were true and it were 35. It's not a big deal, but I'm telling you it's mostly boric acid -- otherwise, it would raise the pH a lot, from 7.5 to 8.9, for example. Yes, there is some tetraborate in there, but only enough to compensate for the slight acidity of the boric acid.

It's important to measure PH with a spa BEFORE you aerate the water. After it's been covered overnight measure PH first thing. Aeration causes PH to rise, and you want to test when it's at its lowest.

Bromine tabs, and MPS oxidizer are both net acidic, and will cause both TA and PH to fall over time. PH up/washing soda/baking soda are alkaline, and do the opposite. Borates just slows down the PH movement.

Lower your ph to 7.5 if it's over that when you test like I said. Ignore PH readings after air jets run. Do not increase TA unless PH falls below 7.5. If you need to raise PH, do it in small steps each day, with either one of the sodas. (note: washing soda and PH up/increaser are the same thing)

Your PH will stabilize.

 

[Kgarriott]

Thank you guys for your responses. I was aware that the pH would rise after the jets, so I always take it as soon as the cover is removed. What might be an issue, is the filter cycle. I'm really not sure how often it runs, and the manual is very vague. I wonder if the aeration from the cycles if they are repeating too often are what is increasing it.

I don't use Bromine tabs, I just use powder. Perhaps I should look into the tabs? Also, what is MPS?

I also have the links above already sticky-ed Thanks for the advice!

 

[ant 83]

MPS is non-chlorine shock.

Make sure that you've read the "how do i use bromine" post linked upthread.

I've never used bromine, because the cost is higher than bleach method. The only advantage bromine has over chlorine (that I can see) is that they have the slowly dissolving tabs that can add sanitation on days the tub isn't being used. That has a nice convenience factor to it.

Also, there is a forum here on TFP for spa/hot tubs.

Spas and Hot Tubs