Posted by 
If you are a new hot tub owner, it can be difficult to know where to start with water chemistry. You might even have a few spa chemicals or supplies but are not sure what they are or what you need to do to keep your water clean.
Our Hot Tub Chemistry Quick Guide is here to help! Learn the basics about the three steps to fresh, clear water:
- Balance
- Sanitize
- Oxidize
Now that you have a good introduction to Hot Tub Water Chemistry, here’s a few more articles to learn even more:
- Hot Tub Setup – A Start-Up Guide for New Spa Owners
- Why Testing your pH & Alkalinity is Important
- What is a Hot Tub Sanitizer and Which Sanitizer is the Best?
- What is a Saltwater Hot Tub?
- Bromine Quick-Start Guide
Have questions about spa water chemistry? Ask in the comments below!
Hot Tub Blog | SpaDepot.com 
What is going on if the alkalinity is reading very high and the pH is reading very low?
LikeLike
Hi srick,
A very high alkalinity is caused by a lot of alkaline materials in the water. If your water has been changed recently, then this may be due to a poor water source. In that case, add pH decreaser until your alkalinity is in balance (this may take more pH decreaser than you expect), then add Easy pH to raise the pH back up. Next time try using a hose-end filter to help remove any impurities. Here are links to Easy pH and our PreFresh filter:
http://www.spadepot.com/Easy-pH—pH-Booster-6-oz-P663C634.aspx
http://www.spadepot.com/Pre-Fresh-Spa-Pool-Water-Fill-Filter-P784C57.aspx
If your water is older than two months, you use the spa very frequently or with large groups of people, then this is due to all of the chemicals, lotions, oil, dead skin, etc, that has been added to the spa. In this case, the best solution is usually draining the spa. Cleaning filters often, shocking with non-chlorine shock after each use, and maintaining sanitizer levels will help, but older spa water is notoriously difficult to balance.
Please let me know if you have any further questions.
Thanks,
Sarah
SpaDepot.com
LikeLike
Thanks for sharing this information, really cool info-graphic Sarah. The products sound great for testing and cleaning water for portable inflatable hot tubs and spas too. Would like to try these products.
LikeLike
I recently purchased a new spa. It has a ozone generator and a UV system. We’ve used UV light in health care for years as a great disinfectant so I knew it would be good for spas. My problem is I can get good alkalinity and ph numbers, but no matter how much Bromine booster I use in conjunction with bromine tablets I can’t get total bromine to register. The best I’ve ever been able to achieve is 1.7 total bromine. It it because of the UV system? I use a non-chlorine shock once a week.
LikeLike
Hi Bill,
There can be a few causes of bromine not registering, but the solution is almost always increasing the shock frequency. Shocking turns inactive bromide (which doesn’t register on a strip) to active bromine (which does).
Try upping the non-chlorine shock to after each spa use, or at least twice per week. Use about 1 tablespoon non-chlorine shock per 150 gallons. Allow the spa to circulate for a few hours, then retest for bromine. If you use the spa very frequently, you may need to use a small amount of chlorine shock periodically to break down the organic matter using up your bromine.
Thanks,
Sarah
SpaDepot.com
LikeLike
just recently purchased a 250 gallon spa tub. decided to use the Cleanwater Blue system. Have followed all the directions and balanced the water properly. Continue to get a green cloudy tub. Filter is also green which I have washed several times. Shock it with several teaspoons of Oxy-Spa after each use. have added 1 teaspoon of di-chlor several times as well. Also use the SeaKlear Natural clarifier to no avail.
LikeLike
Hi Mark,
Green hot tub water is usually caused by excess copper in the water. You may have had copper already present in your water source, or used more Cleanwater Blue than necessary. The shock is oxidizing the excess copper, turning your tub green.
We recommend the CuLator Metal Eliminator to remove excess metals from the water. This product actually traps the metals, removing them completely, unlike most products that suspend the metal particles.
http://www.spadepot.com/CuLator-Spa-Pak-6-Month-Hot-Tub-Metal-Eliminator-Stain-Preventer-P2845
Let me know if you have any additional questions.
Thanks,
Sarah
SpaDepot.com
LikeLike
Hi Sarah,
I tried everything you suggested and it worked perfectly. Thank you so much for your help. Spa chemistry is so much easier now.
Bill K
LikeLike
Is it normal to go through a pound of bromine booster per wk? It seems that every time we test , it shows 0 . We have Bromine tabs in the floater and use the sanitizer after every use.
LikeLike
Hi Robin,
It’s definitely not normal to add more than one dose (as directed on the bottle) per fill-up. Are your filters clean? Have you tried shocking the spa with non-chlorine shock like OxySpa? If not, do both right away and test the bromine again after an hour or so.
Bromide Booster is pure sodium bromide without any added activators, so for the future, always add some non-chlorine shock to the spa when refilling, then at least 1-2 times per week after that to keep the bromine active.
If you have done all of these things but your bromine still isn’t showing up on the test strip, let us know and we’ll help you troubleshoot.
Thanks,
Sarah
SpaDepot.com
LikeLike
So, I use chlorinating granular in my hot tub every couple of days. I figured out that my guy has an allergy to the sanitizer containing potassium peroxymonosulfate (balanced MPs tabs) that I was using weekly to sanitize. His symptoms are equivalent to poison ivy. What other sanitizer do you recommend? The mineral kind? Thanks in advance for your help.
LikeLike
Hi Brenda,
MPS (non-chlorine shock, Oxy Spa, etc.) is a shock only, so it is breaking down bits of organic stuff. Your actual sanitizer is the chlorine granules.
You can skip the MPS and use only chlorine, but you will have to increase how much you are putting in. A bromine system would also work, but I wouldn’t recommend it because I feel that it works best in combination with MPS shock (just a personal opinion – YMMV).
A mineral sanitizer, like a Nature 2 silver ion cartridge, is our go-to recommendation for homeowners. It’s easy, inexpensive and only has to be replaced every 3-4 months. However, it kills microbes slowly and doesn’t shock – so can’t be used alone and you’ll need to keep shocking with the chlorinating granules. TONS of people use N2 cartridges and have amazing results, only needing a small amount of chlorine. There are also mineral cartridges by Frog and PoolRX that work the same, using combinations of silver & copper ions.
Thanks,
Sarah
LikeLike
Thank you for your quick response. I will switch to the mineral cartridges and chlorine. I really appreciate your expertise and chemistry understanding!
LikeLike
I use Bromine and my chemical test shows well balanced. usually i am about the only person that uses it, but lately weve had a lot of family up and using it. I now have a scum and the bottom of the lid and walls are slippery. any idea why?
LikeLike
Hi Onalee,
With increased bather load comes extra contaminants like body oil, perspiration, and detergents. The key to handling these periods of high bather loads is to stay on top of shocking, which breaks down these contaminants. Aim for shocking the water after each time the tub is used. With scum and slippery spa walls, it’s probably time to do a system flush and drain/clean/refill to get your spa back into primo condition.
Thanks,
Brian
SpaDepot.com
800-823-3638
LikeLike