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White substance on shell


Kchottub

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New hot tub owner. Have had it since end of December. I stay on top of my water chemistry, albeit one cloudy water incident which was cleared by a shock. Since then it’s been fine. We haven’t used the hot tub for a couple days and I went out and found a white substance on the walls in two spots on the tub. The main area is where the filters are, the other is opposite side of tub and much smaller. 
 

I use the dichlor bleach method with the trouble free pool app. We are heavy users, and add bleach after each use and shock once a week. Filters were deep cleaned and replaced last week along with a good scrub down on the walls/ top. I check ph/free chlorine 2-3 times per week and all levels once a week with a Taylor test kit. Latest levels below.
 

Since my CYA is high I usually use a lot more bleach than someone with in check CYA levels  my tub is 475 gallons, with a 24 hr circulation pump, and ozonator.  Trouble free pool app calls for about 8.6 oz bleach after each use.  My FC levels are typically low around 1.0 ppm unless it’s been after a shock.

ph: 7.6

TA: 80

CYA: 100 (too high bc I used dichlor for a tad too long in the beginning)

calcium hardness: 350

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Does the deposit  feel rough? If so it's scale deposit. Since it's very hard to lower CH I suggest lowering the TA.

Does it wipe off easily? If so it's just scum. Mostly likely because of your high CYA you are not maintaining a high enough FC level. 1 ppm is WAY TOO LOW for a CYA of 100 ppm. I would suggest a drain and refill and then do dichlor until CYA is at 30 ppm then switch to bleach. Water in a hot tub should be changed every 3 to 4 months anyway so it's time if you orginially filled it in December.

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Thanks for the reply! I drained, purged with ahh-some, drained/ cleaned walls /rinsed, refilled. This is the second purge I’ve done on this tub, the first being done when Delivered.  For this fill, I used dichlor until I was at 30 cya. Have now switched to bleach. 

for the fresh fill, I’ve balanced the water and added 50ppm of borates and enzyme cleaner.  

Current levels:

TA: 50 

ph: 7.6

calcium hardness: 330

It’s been about a week since I did all of that. I am still struggling with low FC on a consistent basis. For instance I used the trouble free pool calculator to shock it with bleach today. It should have hit 12ppm FC, but when I checked again about 10 min after shock, it read 7.8ppm fc. doesn’t seem like that gets high enough to truly shock it. 

I also still have a build up of yellowish gunky stuff (assuming biofilm) in the same spot as original pics show. I wipe the walls consistently with a magic eraser and wipe any gunky buildup in the filter area everyday. We shower before use, wash suits without detergent, add bleach each use, change/clean the filters and shock weekly, use filter cleaner once a month. I almost always have the hot tub gunk ring and now this buildup just won’t go away. The water is clear and levels are fine, just can’t get the gunk under control. Kind of struggling on the FC front and not sure what to do for that. 

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Hi Kchottub:  I realize that you have purged the tub twice already.  Question:  Have you removed the filter(s) when purging?
 I assume you have been following the instructions and NOT overdosing the Ahh-Some gel.  More will not work better or faster.

The gunk you mention can be just about anything that has been introduced into the tub.  However, to me, it does sound like you need to do another purge.  If the gunk is from a biofilm formation, which it may or may not be, there are cases where the slime layers peel off from the colonization similar to an onion peel, layer by layer.  I recommend letting the tub sit with the Ahh-Some in it overnight the day of the next purge.  You MUST not allow the pump(s) to operate while the tub is in this soaking mode.  We do NOT want any of the sticky gooey gunk to adhere to the shell.  So, purge again and WIPE the released gunk off before it dries.  We recommend using an old wet towel to do this.  Many hot tub owners fill the tub almost to the top so the gunk will flow over the ledge and down to the ground.  This works great when the tub is outside and you can simply use a garden hose to spray the overflowed gunk away from the area.  After letting it soak overnight, in the morning run the jets again for 5-10 minutes and drain, ,rinse and wipe the shell clean.  Refill, balance water and raise the free chlorine level, if using chlorine, to about 5 ppm for a day or so.  I really feel that you need to do this.  Your description of your situation is very familiar to me.  Please keep the forum updated as to whether or not this has helped.  Frustrating I know.  Remember this, you will get through this and you will finally begin to enjoy the hot tub.  

 

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Thanks for the recommendation. I have assumed I was going to have to do another purge. 
 

when I use ahhsome, I follow the directions on the bottle and put the filters into the tub while running jets.  Edit to add I also use recommended amounts/ ratios  
 

My tub is outside so I could let it overflow. There would be some water that would get into the cabinet through the head rest mount holes though. I’ve been avoiding that as much as possible. 
 

Something I don’t understand about free chlorine levels is whether the recommended range should be maintained at all times or you’re supposed to get to those levels once a day/ per use. 

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Kchottub:  Free Chlorine levels, or (FAC), ideally should me maintained on an ongoing basis.  Of course this level will diminish periodically and increase as you  add more chlorine.  Free available chlorine is standing ready to oxidize or kill pathogens introduced into the hot tub water from numerous sources.  It will rise and fall much of the time.  The main thing to remember is to never let it get to zero or you will lose the protection free available chlorine affords the hot tub users.

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Thank you! It’s pretty amazing how fast the chlorine levels fall. So yes I do think a purge is in order. I don’t know that I’ve ever been able to maintain a decent free chlorine level since I’ve had the tub. I will update this thread once I’ve done another purge. 

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20 hours ago, Kchottub said:

I wipe the walls consistently with a magic eraser

DON"T! Magic Eraser is an abrasive cleaning pad made of melamine foam and can damage the surface of the tub if s used in the same spot over and over again! IF your tub has a fiberglass surface (most don't, they are molded acrylic then reinforced with fiberglass on the bottom side) then it is a bit more resistant t damage from the magic eraser.

 

56 minutes ago, Kchottub said:

I don’t know that I’ve ever been able to maintain a decent free chlorine level since I’ve had the tub.

That means that something is using up the chlorine (purge!)  or you are not adding chlorine often enough to keep up with the normal chlorine demand in your tub . Are you having a problem with persistent combined chlorine 1 ppm or higher that shocking doesn't eliminate? How often are you testing and adding chlorine? I would recommend testing daily until you get a handle on it. You want to maintain a FC of 3-6 ppm with a CYA of 30 ppm. When the FC hits 3 ppm bring it back up to 6 ppm. This way you will learn how much chlorine loss is normal for your tub under normal usage conditions. When combined chlorine is above 1 ppm shock by adding enough chlorine to raise it to 15 ppm. Ideally you want the combined chlorine to stay at .5 ppm or less but that is often difficult to achieve in hot tubs because they are not exposed to sunlight (UV) and remained covered. IF this is your situation then shocking with MPS can help but as a last resort.

As a general rule of thumb, do a quick test before entering the tub and if it is 3 ppm or less add enough bleach to bump it up (with a CYA of 30 ppm youcan enter the tub as long as the FC is below 10 ppm, btw.) Check again after soaking and if needed bump it up again. IMHO, best way to do a quick check of chlorine (or bromine for that matter) AND pH is by using an OTO/pH test kit that uses liquid reagents such as the Taylor K-1000. These have a comparator that has yellow color blocks on the santizer test, unlike the DPD test kits that have red blocks. OTO will only test total sanitizer but you will know if chlorine (or bromine) is present. IF you let the test sit for about 2 minutes and the color darkens a few shades that is an indicator that combined chlorine is present and you might want to break out the 'big kit' (such as a Taylor K-2006) to check. Be aware that if you have Taylor kits that the pH reagent in the K-1000 is different than the one in the 2000 series of kits because the size of the sample in the comparator is different and they are not interchangeable.

You should be testing with the big kit weekly (or more often if there is a problem) for FC, CC (or TC if you are using a DPD kit and not FAS-DPD) pH, and TA. CH and CYA can be tested every 2 to 4 weeks once they are in line unless you have a lot of splashout or water loss NOT from evaporation since topping off the tub can change these.

Once you get a feel for your tub under normal usage it really becomes easy to maintain.

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51 minutes ago, waterbear said:

DON"T! Magic Eraser is an abrasive cleaning pad

Oof got that tip from a different hot tub community. Will find a gentler way to clean the walls. 
 

My cc result was high (1.8) so I shocked to 15ppm FC. Brought it down to about 0.8- 1 ppm CC. I haven’t been testing for CC all that often so will pay attention to that more too. 

Based on waterbear’s recommended chlorine testing routine, i have been dosing and testing for Chlorine incorrectly. Not testing enough or at the right times (tested mostly after use not before and after). It makes sense now so thanks for the breakdown. We (2 adults) use the tub everyday so I’m testing for chlorine everyday, but haven’t been able to establish a consistent level. Other levels I’m testing weekly besides cya and ch.

I do find we have to top off so I generally retest cya and ch after a top off. I assume most of our water loss is being carried out by swimsuits (not enough privacy to forego the suits yet LOL)

My test kit is the 2006c. I’m still going to purge sometime this week, but I also know some long term maintenance routine changes to make.  Thanks again for all the suggestions. 

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Well yesterday was interesting on the chlorine front. I shocked to 15ppm and was trying to keep the levels between 3 and 6 FC.
 

I ended up adding bleach three more times yesterday. I woke up today and there’s no chlorine at all showing. So dosed it again to 6ppm FC. CC is still about 1ish today. I would assume this is all very telling that I need to purge. I’ll have to hobble along like this for a bit until I can get time to do the purge this weekend. 

so what I understand now is that I created this issue when my cya was out the roof and therefore never had enough of an established chlorine level to take care of the nasties in the tub. I never usually got high enough FC for 30cya let alone 100 cya. So I’m glad I understand those Implications now. Hoping I can get the chlorine levels under control after the purge bc I feel like I have a good grasp on everything else. 

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  • 4 months later...

Finally updating with results. I limped the tub along for a bit bc I didn’t have time to do the water change. 10/10 would not recommend. 
 

When the water was changed again here’s what I did:

- made sure to get FC high before adding Ahhsome. 
- took out filters and washed them separately. 
- dosed the tub with ahhsome, turned jets and blowers to high.
-  Circulated water five times or more by restarting the jets cycle. 
- left ahhsome mixture sitting in tub 24 hours. 
- circulated jets several times the next morning before the drain. 
- while draining hosed down sides and wiped gunk off where I could. 
- cleaned tub walls with a diluted ahhsome mixture in a spray bottle. Made sure to wipe around jets, head rests, filter housing area. Basically all nooks and crannies and was a little obsessive. 
- once it was drained I kept spraying down the sides and refilling the footwell area with clean water. to leave as little of the old water as possible I used a shop vac for the water the drain/ sump pump wouldn’t get. 
- refilled using a hose filter. 
- balanced water, gave it an initial shock and let the tub do its thing overnight.

the next day I noticed a tiny bit of the white gunk in the filter housing area. I was thinking I would have to do another round of ahhsome. However after that, it stopped showing up so I am thinking it was the last bit of residual biofilm being purged. 
 

Since then, I’ve been able to keep FC in the tub without adding to it everyday. So using ahhsome overnight cleared it all completely. 
 

I think this got bad bc in the first round of water, the cya got too high due to using dichlor too long so the chlorine couldn’t sanitize effectively allowing biofilm to buildup.  
 

thank you everyone for the suggestions and advice.  I am feeling much better about maintaining the spa and learned a lot in my first 6 months.

 

 



 

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