waterbear

What are you shocking the tub with, chlorine or MPS?

LaMotte uses DPD to test sanitizer and MPS (non chlorine shock) will test as combined chlorine. This known interference is a limitation of DPD testing. Taylor does have a special reagent to remove the interference from MPS for use with their K-2005 (DPD) and K-2006 (FAS-DPD) test kits. The jump in pH was an interference from the high level of MPS. The pH was not that high. In fact, MPS is acidic and your pH was prbably a bit lower than 7.6 at that point. Lesson here is to never test pH when sanitizer test indicates it is at or above 10 ppm (TC or TB). MPS is a known sensitizer. Stop using it. IF you are using bromine then activate with chlorine, not MPS (I prefer liquid chlorine or plain, unscented laundry bleach (both are sodium hypochlorite, only difference is concentration with laundry beach usually 5.25%, 6%, or 8.25% and liquid chlorine 10% or 12.5%. The generator produces sodium hypochlorite (bleach). Ozone destroys chlorine btw. Is your ozone unit UV-C or Corona Discharge? Is your UV a separate germicidal lamp or the UV in the ozone generator? My guess is that it's from MPS. Dermatitis from hot water does happen in some individuals, it is a form of heat rash and can appear as small, itchy bumps or a generalized redness of the skin. There can be an underlying contributing medical condition.

are you asking for one or telling us about one?

Post a full set of test results (and how they were done such as strips, drop based kit such as Taylor, Meter and reagents such and ColorQ, Dealer testing and how what they used--strips, disc and meter, liquid regents) and what sanitizer system you are using. Also, if you can, post a picture. It will really help. This way we will have a good idea of what might be going on. I am particularly interested in what sanitizer you are using and also your calcium hardness, pH, and total alkalinity. Also, if you are using stabilized chlorine such as dichlor or trichlor what your cyanuric acid (stabilizer) level is. I can think of at least 4 possible causes for what you are describing and we need to narrow it down.

This is because teaspoons and tablespoons are volume measures and they are specifying a weight measure.

According to "15 U.S. Code § 1453 - Requirements of labeling; placement, form, and contents of statement of quantity; supplemental statement of quantity" it would be weight since volume measure is specified to use the largest volume measurement which means it would say '1 pint". Also, since the Bottle also state that it is 453 grams this is a weight measurement and not volume as I originally stated in a previous post, and the rounding of 453g is specified in "NIST Handbook 133, Fourth Edition" for weight labeling. If it were a volume measurement the bottle would also be labeled in either milliliters or liters, most likely as .47 liters. This is assuming it is a US pint and not an Imperial (UK) pint which is 20 ounces. The labeling in both grams and ounces can be clearly seen in the attached picture confirming that it's by weight. Also, the dosing would be by weight.

And you made the assumption that the phone rep knows what they are talking about. Sadly, that is often not the case.

Clean the filter when you get a rise of 8-10 psi on high speed (if you have a variable or 2 speed pump). For example, if your initial PSI reading is 20 with a clean filter you don't have to clean the cart until it rises to 28-30 PSI.

You are using stabilized chlorine which adds cyanuric acid (stabilizer). the FC level you need to maintain is determined by the CYA level. If the CYA is too high the chlorine is essentially deactivated which allows things to grow in the tub. The test kit you need is a Taylor K-2006, which uses FAD-DPD titration for testing chlorine (NOT the K-2005 which uses DPD colorimetric test for chlorine). It will be worth every penny, Also, you cannot maintain a stable pH without knowing the total alkalinity. Testing for pH and total chlorine (OTO test for chlorine) which is what your test kit does) is ok for a quick daily test but you need a full test kit to determine what's going on in your spa. The information you provided is essentially useless without a full set of test results (Free Chlorine, Combined Chlorine, pH, Total Alkalinity, Calcium Hardness, and Cynauric Acid which are commonly abbreviated as FC, CC, pH, TA, CH and CYA) I would recommend reading the "sticky" posts at the top of the hot tub water chemistry section of the forum and pay particular attention to the Dichlor/Bleach post and the ones that I wrote. In a nutshell, get a Taylor K-2006, watch the videos on the Taylor Technologies website to properly learn how to use it, test your water, and post the results.

Other than the fact that your bromine is a bit high these numbers look good for a bromine spa. MPS is acidic so it will deplete TA so when it drops below 50 ppm use baking soda to bring it up. 50 to 70 ppm is a sweet spot for most spas. High sanitizer levels can cause DPD tests to bleach out and your pool store is using either testing discs or strips with meter to give you results like that. IF your Taylor kit is a k-2006 (FAS-DPD testing for bromine or chlorine ) then bleach out is not really a problem unless your bromine is really through the roof and I would trust it over the pool store test. IF it's a K-2005 (DPD testing) then it can and will bleach out at moderately high sanitizer levels and indicate that your bromine (or chlorine) is much lower than it actually is. This can affect pH and TA readings since high sanitizer will cause inaccurate pH readings (pH will seem to be much higher than it actually is because the pH indicator, phenol red, is converted into bromophenol red or chlorophenol red both of which have the same color changes as phenol red but at a much lower pH range and the purple red color that indicates a pH of 8.2 or higher with phenol red indicate a pH of 6.7 or higher with chlororphenol red or 6.8 or higher with bromophenol red. High sanitizer can also bleach out the indicators used for TA testing leading to off resuts, particularly with colormetric tests (read with a meter) vs titration tests (such as Taylor's).

Salt water chlorine generators require adding salt to the water to a certain PPM level (determined by the manufacturer) and some also require the addition of stabilizer too. It's done at fill up and after every water change. However, this does not mean that you do not have to test your water. You still need to monitor chlorine, pH, total alkalinity, calcium hardness, and possibly cyanuric acid (stabilizer).

Both products are trichlor, a stabilized form of chlorine. My guess is that your stabilizer is too high which "deactivates" the chlorine and allowes "nasties" to grow. (White water mold is bacterial, btw.) What is the CYA level in the water and where do you maintain your FC? Posting a full set of test results would tell us a lost more!

not unusual either. stuff can accumulate in areas of low water flow, especially on a material such as a gasket that has an affinity for deposits to adhere. Your situation is fairly common. gunk accumulates when there is not a lot of water flow and on materials that the gunk can stick to readily. If it makes you feel better thinking your situation is unique then go for it but it's really not.

Yes, it's a common occurrence. Most spas get a scom line so many don't realize aromatherapy products can add to it but if you think about it you realize it's just common sense.

Just about all aromatherapy products will increase sanitizer demand and the sanitizer will oxidize them. It's a fragrance so it probably has essential oils (most likely synthetic) or derivatives. When they break down it's very poosible for them to form scum.

IMHO, yes.

We have a winner!

Looks like you are doing fine!

are you just dumping in chemicals and hoping for the best or testing your water to determine dosing. What other chemicals are you using that is causing your TA to crash (usual culprits are triclhor, dichlor, and MPS). TA should be fairly stable unless there is a constant source of a low pH product being added regularly. Post a full set of test results and list the chemicals you are adding and how frequently and we can take it from there.

Mineral cartridges for chlorine use silver nitrate and sometimes a zinc salt in a matrix to supply the silver ions. Mineral cartridges for bromine use silver chloride in a calcium carbonate matrix. Silver nitrate will react with bromine to form silver bromide which will precipitate out.

For dry ingredients an ounce is by weight. For liquid ingredients it's by volume. Same as in cooking. Think about it this way. An ounce by volume of water, mercury, and heavy cream all will have the same volume ( but different weights), while an ounce by weigh of ball bearings, baking soda, and feathers would have the same weight but very different volumes. With pool and spa dry chemicals some might be fine powders (dichlor), some might be pellets (CYA), and some might be chunks (calcium chloride dihydrate) so an ounce by weight would not be the same volume for any of them. The ONLY time an ounce by weight and by volume are the same is for water. This is considered common knowledge (and common sense) so it's not on labels. An inexpensive digital kitchen scale and PLASTIC kitchen liquid measuring cups and spoons (and perhaps a chart that shows equivalences such as 16 Tbls. in a cup and 3 tsp. in a Tbls.) are necessary pool and spa equipment that is often overlooked!

Post what sanitizer and other products you have added to the water (any balancers, clarifier, algaecides, etc.). DId you add the dicHlor and what did it do to your CYA? (Dichlor adds 9 ppm CYA for every 10 ppm FC added!) Mustard Algae usually does not just grow on gaskets. It will usually be on the walls and floor of the tub and is a bright mustard yellow color. White water mold (which is bacterial) is usually seen as free floating flakes in the water that disintegrate when touched. I've never seen them collect on a gasket like in your picture. I suspect it's more likely some sort of scum in the water from bathers (suntan products. lotions, creams, hair products, normal body oils, etc). They usually form a scum line in the tub but can collect behind jets since, as @RDspaguysaid, not much water gets their and it's very possible for matter to collect. Do you also have any kind of scum line in the tub? One of the purposes of the filter is to collect such matter, so finding it in the filter means the filter is doing what it is supposed to be doing. White water mold would not really collect in the filter nor would mustard algae. I prefer to drop a Scumbug, Zorbie, or Sunsorb or one of the other oils absorbing sponges in the water to deal with scum. They are inexpensive and is the first thing I would try to see if it eliminates or lessens the problem You can also try an enzyme product but I haven't found them to be any more effective than an oil absorbing sponge and they cost a LOT less.

I am very interested in how you determine this since OTO (orthotolidine) , DPD (diethyl-p-phenyleneldiamine), FAS-DPD (ferrous ammonium sulfate / diethyl-p-phenyleneldiamine), and SYD (syringaldazine) cannot differentiate between chlorine, bromine, iodine, nor MPS. A bromide bank is NOT necessary if you are adding both sodium bromide and an oxidizer at the same time. In fact, this is how two step bromine works. The one step products just mix them together so you do not need to dose with 2 products at the same time. Perhaps you should learn a bit more about the chemistry behind the use of bromine in a hot tub. If there is no bromide bank it means that you have to add sodium bromide and an oxidizer to create bromine sanitizer, once the bromide reserve is established then only the addition of an oxidizer is necessary to generate bromine sanitizer.

Your high sanitizer demand sounds like it might be a biofilm problem. When is the last time you purged your spa? What are your thoughts @RDspaguyand @Ahhsomeguy?