Rubber type growth above waterline, what is it??

[Scuttler]

I'm in a hard water area in the UK.

Tub is a Leisure's Edge LE852 and was installed new around 2 years ago.

The tub came with a Spa Frog system which has failed to work from the outset. Tub was set up with Bromine as the sanitiser but basically we had to shock the tub on a daily basis as it seemed to flatline. pH level started in spec around 7.2 but would drift to 6.8 and possibly lower (acidic) within a couple of days of a fresh fill. TA was fairly rock solid at 180ppm-240ppm. In the end (5 water changes and 6 months in) we ditched the spa frog and used a floating dispenser. That resolved the Bromine level issues. I suspect that the ozonator has never worked and hence the inability to get the pH levels to stay above 7.0. I've used Frog test strips and a lovibond test kit and found that the readings disagree with each other in terms of exact numbers but the essence of the reading is the same (TA steady, pH low).

Around the 6 month mark a white "chalk" line started to appear just above the water line  (about 1/4=1/2" wide) but no matter what cleaning chemicals were used nothing would shift it. We tried Stain & scale Inhibitor, Waterline Cleaning Gel, Swirl Away II as well as a cloth soaked in vinegar and another soaked in Limescale remover. It wouldn't shift.

The dealer had been out several times to help us but they have drawn a blank too.

Roll forward to now and the band above the water is now around 4" wide. Today I had some time to actually spend investigating it further and so got some waterline cleaning gel and a tub scrub pad to see whether I could shift it. I noticed that it's actually a soft layer that appears to be growing. I can dig my fingernail into it and peel a little away. I can only describe it as like bitumen paint or a skin. It stretches slightly and is a greyish colour. When I remove it I can see the acrylic layer beneath so it doesn't appear to be damaging the gel coat or acrylic but no one seems to know what it is or more importantly how to get rid of it. I can also see it on some of the jets that have been exposed as the waterline has dropped.

The tub probably gets used around once every two weeks (most of the use is in the summer).

The tub is 8' x 8' and I've managed to remove about 2"x1" of the growth.

Hopefully the pictures below can help shed some light on the matter. Does anyone know....

• What it could be?
• How to get rid of it?
• How to stop it from coming back?

Any help would be greatly appreciated.

[dunecritter]

This is strange and I have been looking forward to what kind of reply this thread might get...But not a lot of ideas yet?

[Fisher25]

I get the same thing. I think it has to be a body oil issue or a water you use to fill tub issue

[Scuttler]

@dunecritter nothing so far, tub dealer is contacting local plastics company that specialise in pools and boats to see what they say. They've given me an acrylic sample to test steam cleaning on before I give that a try


@fisher25 have you been able to remove it? Nothing I've used seems to touch it other than scraping the top layer off. I'm almost at the point where I'm considering using one of those buffing pads on a drill or sander to remove it!!!

[Scuttler]

Latest is that the steam cleaner seems to soften the top layer and make it easier to lift the rubberised growth but underneath that is a tacky layer and then a harder layer that you can't see when wet but once it dries fades to white (almost like a calcium build up). As the pics show, everything below the waterline is fine but the growth starts at the water line and seems to grow up from that point.

The dealer has given me some deep clean chemical that you apply to the surface and agitate, leave for 20 minutes then rinse off. It's not really having a huge impact so I think I'm resigned to removing as much as possible with the steamer and then buffing afterwards. Wish I knew what it was. Have had the water tested using a computer tester at the dealers and that seems to concur with the readings I get using strips or the Lovibond kit. Pretty sure it's nothing to do with body oils as the tub doesn't get used a huge amount.

[Scuttler]

Plastic company came out and said the lacquer coat is breaking down. They peeled back the growth and you can see a line of what looks like lacquer.

Dealer has refuted this stating that tubs are not lacquered, only acrylic over fibreglass. Is this right?

After an internet search they claim the "growth" is biofilm. We've followed all the instructions about wiping the tub down, quarterly drains, cleans and refills. Filter changes every 6 months. Could this still be biofilm and how could it have infected the tub when we've been so vigilant?

[dunecritter]

Not Lacquered over the Acrylic...Straight Acrylic. If the tub has had a repair it is possible that they might have used a lacquer with a catalyst to gain that shiny look again but I doubt it...besides it would have been only in a certain repair and blended out to match then buffed. Strange that it's only above the water line....I'm not too savvy on Bio film etc...but that sounds like the best bet thus far....Maybe raise the water line way above normal to submerge the effected area and try some Bio Film remover like AAsome? Not sure on this spelling but rthere are a few posters on here that have used that product with claimed excellent results? Maybe ChemGeek might be able to chime in and give his input...He may not have a clue either but he's probably your best bet for input.

[Vinny]

It is probably not a biofilm if the cover isn't showing the same signs. The cover touches the shell and the biofilm would get onto the cover.

You state that you steam clean the tub - is that before or after the problem started to happen? I'm thinking that its possible that the acrylic is damaged from the steam ~ below waterline no problem/above waterline problem. Its hard to diagnose a problem that has never been sent before but it sounds like to me that the tub is delaminating for some reason. Maybe the tub was chemically damaged but I would think that the cover would show signs of chemical damage as well unless you used a product that was too strong for the acrylic and didn't use the same product on the cover.

Ozone and PH was mentioned and one has nothing to do with the other.3

I would go with what the plastics company is saying and think that whatever phyical layers the tub has on it are the problem. I guess you could have a piece of whatever it is analyzed and knw for sure.

[beachboy]

Key part to all your problems seem to be the Hard water area,your alkalinity is high and your pH low.All hot tubs/spas are designed to work with Balanced water and any deviations from the norm can invalidate your Guarantee.
There is certainly Calcium scale attached to the sides and it being at waterlevel is the clue (like a bathtub) that it has bonded with Oil/grease and adhered to the sides,are you using a clarifier to aid your filter?
I use a Chitosan based clarifier made from chilated shrimp shells that "Grab" the oils and trap them on the filter,this greatly reduces the scum line and leaves the tub water clear.
As for breaking down Calcium then an acid based product needs to be used to disolve the calcium and Oils/grease,Most quality Hot tub flushes should do this as they are designed to break down Calcium and eliminate Biofilm from the dark recesses of the Tub that we cannot see.I dont know if you can name brands on this site so i have not but if it is ok to name products then i will.
The low pH is worrying as Bromine is an Alkali and should raise pH not lower it? and as you already have very alkaline water i fail to see where the low pH comes from,Not sure about the Spa frog etc as i am a Bromine/Chlorine man and are wary of the gimiky add ons that companies use to assist in sanitation (Voodoo products).
Please try and keep your pH above 7 or else you will find jets etc rusting and you will have no recourse.
As for using a flush the one i use recomends taking out the filter and opening all the jets run the product through the tub on full bore to reach all parts of the pipework and fill above the Calcium bonding so it can work on it.You also mention changing your filter every 6 months?Is this a new one or a clean up?Do you empty flush and refill every 12 weeks regardless of usage?
I can more or less say with my hand on my heart that it is nothing to do with the finish of the Tub and is certainly water chemistry based and the Calcium is bonding with something(do you use Oil based smellies in there ?)

[beachboy]

On re reading the post on your tub i see that you use the tub infrequently so it could be Bromine staining.
With the cover on a lot it could be venting off and staining the Acrylic above the waterline.
When shock dosing a Spa always leave the cover off for a bit as this is when the underside gets damaged through Chemical reaction.

[Scuttler]

I've found a way to remove the growth back to the acrylic now. It actually coats everything from about 2-3" below the waterline right up to the lip of the tub but is thickest at the waterline. It appears to be glue and the latest thought is that we may have had a bad batch of bromine and the bonding agent has broken down.

I've cleaned all traces from the tub itself and am now working my way round the jets which were close to the waterline and the jet controls (notice they are whitish in the pic....well they should be graphite but the dealer put it down to bleaching.....but nope it's actually the same stuff that's on the tub)

The jets are going to take forever to clean up and the filter skimmer I may end up replacing completely, but at least things are looking up

I will probably have to deal with biofilm once I get the tub up and running again as it's been empty for about 7 months now whilst I've been trying to fix the issue!!!

[Quickbeam]

Just curious, what did you use to remove the growth?

[Scuttler]

Very mild xylene solution to soften it. Scrape away with a plastic scraper then polish off with cloth dipped in diluted methylated spirits.

[Tman122]

Try a filter for your hose next time you fill and see if it helps.

[Scuttler]

Try a filter for your hose next time you fill and see if it helps.

We already use one