How Often Do You Change Water ?

[treynolds]

I was wondering what others here think about the frequency of water changes...

We purchased our Bullfrog Tadpole 361 used this last summer and filled it up in August. Due to a combination of below freezing temperatures and in general sucky weather here in Seattle during much of November and December, I JUST THIS LAST WEEKEND had a non-freezing, partly sunny day to drain, clean and refill my spa.

That's 4 1/2 FULL months of using the same water, which to me seems very icky.

It ocurred to me that to fill up the spa took about 3 hours with a small-diameter hose, so perhaps the cost of the water to fill isn't that great?

The big thing that got me was the water took FOREVER to heat... That's 240Vs running for about 8 hours to get 40 degree water up to 104.

I was thinking that changing the water once a month instead of every 3-4 months would be great until I thought of the energy costs.

What do others think ???

Tony

[quizkid22]

3-4 months is the norm....I got my tub in Sept....drained in Nov (thanskgiving)...will do it again when we thaw here in Mich. in March (I hope).....

Time frame for your water to heat up is just about right. I have a smaller tub and my water was at 50 when I filled and it took 8 hours. My November bill was through the roof....wife is still on my case for that.

Everything I have read and been told say 3-4 months. Just keep up with your sanitizer....

I was wondering what others here think about the frequency of water changes...

We purchased our Bullfrog Tadpole 361 used this last summer and filled it up in August. Due to a combination of below frezzing temperatures and in general sucky weather here in Seattle during much of November and December, I JUST THIS LAST WEEKEND had a non-freezing, partlt sunny day to drain, clean and refill my spa.

That's 4 1/2 FULL months of using the same water, which to me seems very icky.

It ocurred to me that to fill up the spa took about 3 hours with a small-diameter hose, so perhaps the cost of the water to fill isn't that great?

The big thing that got me was the water took FOREVER to heat... That's 240Vs running for about 8 hours to get 40 degreee water up to 104.

I was thinking that changing the water once a month instead of every 3-4 months would be great until I thought of the energy costs>

What do others think ???

Tony

[mjs]

I don't know that there is a "norm", but I've heard 3-4 months as the max you should go.

In discussing how often I change my spa's water, I find it useful to mention WHY I'm changing it.

In the two years I've owned the spa:

- I've changed it ONCE because I couldn't control the cloudiness,

- All other times, I've changed the water because of foaming.

For me, foaming is obviously the critical factor, and I change the water typically every 6 weeks.

I should also add more info:

- I use the spa several times a week year around,

- I do not jump in if dirty or sweaty but will shower first; I do not take a shower if I seem to be "clean",

- I use a defoamer which helps, but does not eliminate the problem. I also know using too much defoamer will in turn icrease cloudiness.

- My spa if a "foam generator"; that is lots of jets, several pumps, lots of air, and I like them all on HIGH

OK, that's my story and I'm sticking to it!

[Jim_The_Jim]

Typically up to 6 months on ions and over a year with the Eco One system.

The only reason to change the water is high total dissolved solids. If you are putting in less chemicals, less solids are dissolving.

The water in your tub is many millions of years old, it is the condition of it that determines when to change the water. With proper filtering, sanitizing and pH balance, you can go for quite a long time.

It will stay clear and clean if you follow standard care instructions. It is not a bath tub.

[Chas]

Jim_The_Jim sez, "The water in your tub is many millions of years old, it is the condition of it that determines when to change the water. It will stay clear and clean if you follow standard care instructions. "

Not being as ols as you must be, I couldn't comment on the age of water, but the point is that the content of your water will chagne over time as some of it evaporates and things get added to it. Different systems make different claims, but I have gone with three to four months as an interval. Most of the instructions I have read recommend a change interval of three or four months.

Thing is - some folks like to make it sound like it is some great deal to stretch the interval. I love the feel of fresh water, and it is generally far easier to care for.

Water is the cheapest 'chemical' you can add to your tub.

[poollady]

Jim_The_Jim sez, "The water in your tub is many millions of years old, it is the condition of it that determines when to change the water. It will stay clear and clean if you follow standard care instructions. "

Not being as ols as you must be, I couldn't comment on the age of water, but the point is that the content of your water will chagne over time as some of it evaporates and things get added to it. Different systems make different claims, but I have gone with three to four months as an interval. Most of the instructions I have read recommend a change interval of three or four months.

Thing is - some folks like to make it sound like it is some great deal to stretch the interval. I love the feel of fresh water, and it is generally far easier to care for.

Water is the cheapest 'chemical' you can add to your tub.

Every 4 to 6 mos. is about right

[ozonator]

I'm still a hot tub novice, but from my two years experience, it depends a lot on the season. In this past Winter, I got 3 months before changing it this weekend. In the mid Spring with falling seeds and Fall with leaves (there are many large maple trees around me), 6 weeks to as little as one month is about right. Also, use by three or four teenagers can change that dramatically. There is nothing like the feel and smell of fresh water. I don't know, but there seems to be a point when the water just cannot be made to smell right or have the right clarity anymore. Also, it can be quite clear with the pumps off, but when they are on, the clarity is reduced considerably. That's when I change it. But it is also likely that I can improve my knowledge of chemicals and thereby reduce the frequency of changing water.

Bottom line: There is nothing like the feel and smell of fresh water, and I like the smell of Bromine in fresh sparkly water.

[hottub.pool_boy]

Since the water change part has been covered, I'm interested in the 8 hours for 40 degrees. 7-10 degrees an hour is a good average for heating spa water w/ 240v.

You probably knew this, but make sure your air controls are off when you're initially heating the spa or when you're done using it. Just a thought.

[treynolds]

Since the water change part has been covered, I'm interested in the 8 hours for 40 degrees. 7-10 degrees an hour is a good average for heating spa water w/ 240v.

You probably knew this, but make sure your air controls are off when you're initially heating the spa or when you're done using it. Just a thought.

All good input from everyone, thanks!

Please be aware that in the original post I was talking about a 60 degree temp rise over 8 hours, not a 40 degree rise, which would be a typical summer-time water temp.

It looks like 4 months is working out pretty well for me. That way I only have to buy 3 SpaFrogs per year. I do agree on the quality and feel of fresh water, but I think that can be approximated by staying on top of the pH.

There are only two of us, and the tub probably gets used a total of 4 times per week, once or twice with the two of us and once or twice with just one person.

We also have the rule that if you're not clean, you must shower first. We had a cloudy water episode over the Christmas break and I suspected that it was due to my daughter and some of her friends using it without showering first, i.e. they had makeup and body lotions that clouded the water.

We're pretty light with the chemicals because of the low use: I test the water and add a small amount of dichlor and spa shock once a week, balance the pH as needed along with alkalinity increaser and hardness increaser. The only other thing is that we add a couple cap-fulls of 6% chlorine bleach after each use.

Almost no chlorine or bromine smell and clear water.

Tony

[billy sharpstick]

In the two years I've owned the spa:

- All other times, I've changed the water because of foaming.

For me, foaming is obviously the critical factor, and I change the water typically every 6 weeks.

the only time i've had a problem with foaming is when i let people in the tub wearing clothes. barbaric behavior in itself, but most washing machines don't rinse out all the detergent adequately.

bill keiser (who will never be caught with his pants up in a tub!)

[chem geek]

Though it is true that the need to change the water is dependent on what has built up in the water, it depends on WHAT those Total Dissolved Solids (TDS) are composed of (and it's not really TDS that is the problem anyway, but more on that below).

If using chlorine for disinfection, then for every 1 ppm FC of chlorine that is added, this will result in 0.8 ppm of salt (chloride measured as ppm sodium chloride). If bleach is used, then this is doubled, so every 1 ppm FC results in 1.6 ppm of salt since the liquid forms of chlorine have an equal amount of salt along with the chlorine as a byproduct of dissolving chlorine gas in water. One can have very high levels of salt in the water before there are any issues and in fact many people like the feel of saltier water. Even if one added 4 ppm FC per day every day, then even after one year using bleach one would still only have added 2336 ppm salt which is still less than the 3000 ppm typically found in saltwater chlorine generator (SWG) pools. Yes, corrosion risk is increased somewhat, but the water will not fill icky due to the salt.

If one adds Muriatic Acid to lower pH and baking soda (or Alkalinity Up) to raise TA over time, then sodium chloride salt is also being added, but the rise in pH can be controlled by setting a lower TA target so this buildup can be minimized.

If one uses Dichlor only, then there will be a buildup of Cyanuric Acid (CYA). This results in lower disinfection from the chlorine and for every 1 ppm FC added by Dichlor, one gets 0.9 ppm CYA. So over one year if 4 ppm FC were added every day, then one would have 1314 ppm CYA which is a huge amount, but again shouldn't feel "icky". Some of this CYA gets oxidized over time, but it still builds up if you use only Dichlor and don't change or dilute the water. The main problem here is that higher CYA levels make chlorine less effective (most of the chlorine is bound to CYA and this combination is not a strong sanitizer).

If one uses Bromine, then the bromine itself will generally not buildup very much as it just goes back and forth between bromide and bromine (unless you keep adding it, such as via a floater). What builds up are the byproducts from the oxidizer used to activate the bromine. If this is chlorine, then this results in salt as described above. If this is non-chlorine shock, potassium monopersulfate (MPS), then this results in sulfates which do not feel "icky" and are relatively benign except possibly in high concentrations with plaster/grout.

Since the above salt and sulfate gets measured as TDS and is not a problem, where does the "icky" feeling come from? It's from organics such as oils from the skin and lotions (including suntan lotion). If one cleans oneself (especially with soap and water with a thorough rinsing) before using the tub/spa, then this helps minimize this problem. There are also organics and ammonia-like products that come from sweat, but those are more readily broken down (oxidized). So the main problem is with organics from oils, dead skin, etc. Some of these are oxidized by the sanitizer such as chlorine, but chlorine does not oxidize organics very well without help such as from the UV rays from sunlight. This is why outdoor pools that are properly managed with chlorine rarely measure any combined chlorine whereas indoor pools and tubs/spas have more of a problem with combined chlorine (unless non-chlorine shock is used).

The regular use of non-chlorine shock (MPS) helps break down organics, similar to "burning" them into carbon dioxide and nitrogen gasses and water. MPS *may* be helped in its oxidation by some metal ion catalysts, but I'm following up on this with Dupont. Non-chlorine shock also oxidizes ammonia before chlorine gets a chance to combine with it so combined chlorines are avoided completely.

Enzymes catalyze (speed up) the oxidation of organics and can make chlorine more effective in that way, though MPS is still the better oxidizer for this purpose.

I suspect that most people under-dose the amount of non-chlorine shock (MPS) needed to break down organics in the water. Though Dupont recommends one pound per 10,000 gallons in a pool once or twice a week, they recommend 1-2 ounces weight per 250 gallons in a tub/spa after each use (or once a week if not used). I think these recommendations are on the high side of what is needed (not a surprise, since the recommendations come from a manufacturer) and of course this will depend on the number of bathers since it's all about using enough MPS to oxidize the amount of organics that have been added to the water, mostly from people. But most people just dose an ounce or two per week and with daily tub/spa use, that's probably not enough if you want to have your water last longer.

What I don't know is how completely even MPS or sanitizer+enzymes oxidizes organics. There may still be some leftover remnants that don't get handled. The hardest to handle are saturated fats, waxes and the even harder alkanes (or paraffins). Fortunately, these substances are also mostly insoluble in water and are often part of what makes up "scum lines" (along with soaps) and may also get caught in the filter if consolidated. Interestingly, Cyanuric Acid (CYA) is an organic so in theory it should get oxidized over time as well, though slowly, but this indicates another class of organics that resist getting broken down (triazine rings).

Technically speaking, the Total Dissolved Solids (TDS) are not "icky" by definition because if they are fully dissolved then you generally won't feel them (ignoring their oxidation potential) unless you get out of the water, which then evaporates, and you feel what is left, such as salt. The "icky" part is most likely insoluble organics that are not dissolved and that I described above.

Richard