Foam that isn't?

[watson524]

Hi all,

500 gallon hot tub. Water was last changed 3rd week of May (5 months after initial fill). It's only been my husband and myself in and never with suits on. In the last month or so, we're getting "foam" in the water in the corners depending on which jets are on. The water is fizzy but I understand that's normal and can get worse as the water ages. This foam doesn't happen with just the jets on, only when the air is on too. We scoop it out as much as we can but it's getting annoying. We just changed the filters today and it seemed worse tonite so my suspicion is they filters weren't rinsed well enough but this isn't a soap film... it leaves no scum line or anything and it's not slippery. When the air gets shut off, the bubbles go away right away. And with the jets off, the water is crystal clear and sparkles.

We use the dichlor then bleach method. Last time around we had a scum bug in the water but we've tossed it because it was getting too scummy but have another one on order. We're having friends over this weekend and I'd rather not dump the water before then (plan to dump it sometime after before we get into too cold here in Northeast PA).

Our weekly test results were:
pH: 7.6
CH: 90 (well water, never had to take the calcium up before and since it doesn't seem to be a soap type foam, I'm wondering if we should mess with it)
TA: 60
FC: 2.4 (before the soak tonite)
CYA: 40
Borates: ~50

Wondering if anyone has any ideas.

thanks!

 

[chem geek]

Raising the CH to 120-150 ppm should help some with the foaming. If you wanted to raise your water hardness further without risking calcium carbonate scaling, you could add magnesium sulfate (i.e. Epsom Salt) or magnesium chloride since both calcium and magnesium will bind to soap-like molecules (salts of fatty acids) and precipitates them to prevent foaming. Ironically, it's when you have the hardness higher and prevent foaming that you would be more likely to get a scum line, but that is something you can wipe off which may be easier to do than scooping soap suds.

The scum bag/bug is usually the best way to remove floating organics (usually oils) from the water. Another alternative is to use enzymes to help oxidize such organics.

How often have you two been soaking -- how many days per week and how long for each soak? With the Dichlor-then-bleach method you should be able to use the following rough formula for the Water Replacement Interval (WRI):

WRI (days) = (2/9) x (Spa Size in Gallons) / (# of Person-Hours per Day)

So for your spa if you were soaking every day with 2 people for 30 minutes that would be WRI = (2/9) x (500) / 1 = 111 days or 3.7 months. You've gone 5 months so either are using the spa less than I assumed or you are pushing the limits for the amount of organic buildup in the spa given that you do not have an ozonator. The ClearRay doesn't help much for that and if its too powerful it will actually use up more chlorine.

By the way, don't forget to use Dichlor one day each month to help maintain the CYA level. You might test for the CYA level to be sure it's not too low. Chlorine slowly oxidizes CYA in hot tubs at the rate of roughly 5 ppm per month.

 

[watson524]

Thanks for the tips. I'll probably bump up the calcium a bit. I have some Leisure time calcium booster that the store gave us when we got the tub but have never used. Looks like an ounce adds 7ppm in 500 gallons so I'll target 8 or 9oz and wait for the scum bug to arrive and toss him in. In the meantime, I have some oil absorbing sheets in the garage (gray on a roll with small holes in them). Do you think there's any harm in floating some of them in the tub?

I was calculating it out a while ago with your formula and thinking we should be getting longer out of it. Lately, it hasn't been used as much because of crazy schedules. Looking at our log book, in the past 4 weeks (28 days) we've been in a total of 8 person hours or 0.29 person hours / day. So the WRI should be 383 days which seems crazy high. If I take the data back to our last water change, 5/29/15 or 137 days ago, we had 33.5 person hours or 0.24 person hours / day with a WRI of 462 days. Even more crazy to expect.

From that test I was doing before with the ClearRay eating chlorine, I've left it unplugged so we're not using that. Even tho we're not in much we test at least every other day and it doesn't get to 0 ever. We're also good about swapping out the filters every 4 weeks.

I test the CYA every 4 weeks and use dichlor accordingly. Last test for that was 10/4/15 and it was 40ppm so I figure I'll be due again in a few weeks to use the Spa 56.

I was hoping we could get to at least the end of this month with the water so that I, theoretically, can get through the winter in NE PA without having to do the drain and refill. Ahh-some already on standby (never did hear back from my email to the company on if the product changed so I'll have to call them) and a water meter for the hose so we know exactly if it's 500 or more gallons going in.

P.S. The new scub bug came today so I threw him in after I added the calcium increaser (still have to test actual level, will do that tonite) but I'm still curious about those oil sheets in a pinch

 

[pooldv]

Don't know about the oil sheets but epsom salts has helped with minor foaming in my tub. And it helps the sore muscles, magnesium and smells good too!

 

[RNDEBBIEROSE]

I have a question for pooldv concerning the epsom's salts...how much would you recommend adding to help with foaming? I also have this issue. Thanks!

 

[Pilotwerx]

We used to suffer from the same issue. I am not sure of the chemistry, but since converting to salt water it is no longer a problem.

 

[chem geek]

Note that if you thoroughly rinse your swimsuits and make sure you don't have soak or oils on your skin (i.e. that you are clean getting in) that will help a lot.

 

[pooldv]

I don't really measure it anymore, but it is probably 2-3 cups after refill and a cup maybe once a month to refresh it.

 

[watson524]

Our calcium is at 150 right now and our new scum bug came so he's in there. We didn't go in last nite but running the air it seems like there's less foaming and we definitely feel the line around the edge now but like you said, easy to wipe off. Weird how our WRI numbers are so high but I'm wondering if marathon training season for my husband has caused some of this. More massages (tho he does shower before going in after those) but body glide etc etc may have junked up the water more than normal.

 

[pooldv]

That is likely the cause. Lotions/oils are the worst for that. Hard to wash off in the shower and soaks right off into the tub.

 

[watson524]

This is why I will never run a marathon! Too many side effects

 

[pooldv]

Right! I'm with you on that!