Creosote and chlorine

[bridgman]

Hi all;

First post here, but I've been lurking and learning for a while. I realize this is probably just a variant of the old "how much chlorine do I need to oxidize a dead porcupine" question, but it's new to me anyways.

Running a wood-heated hot tub, using dichlor/bleach for sanitizing. CYA around 25-30 using a Taylor kit, just on the cusp of switching to bleach after the most recent refill. Everything seemed to be fine until the last couple of days, when a thermometer failure resulted in the water getting hotter than planned, so I closed the air intake with the fire still burning rather than letting the fire burn down normally. The Snorkel chimney is arranged to keep rainwater from running into the stove, but the downside is that if you do make a lot of creosote some of it can drip into the water. Normally I burn hot fires and creosote isn't a problem, but damping the fire down mid-burn made a lot more creosote than normal.

I added about 8 oz of bleach after using the tub last night, which is normally enough to give me a few ppm of FC the next evening, but when I checked this morning the chlorine level was 0. Added another 6 oz bleach, checked chlorine level after mixing, then re-checked a couple of hours later -- 0 again. Added 4 tsp of dichlor and checked chlorine level immediately after mixing it in -- 5-10 ppm, no problem. Will check FC/CC as soon as I get home.

I gather from this that chlorine probably does try to oxidise creosote and that's why my chlorine is suddenly disappearing -- guess I'm wondering if MPS might be a better choice or if there is some other magical "creosote-B-gone" chemical I haven't heard of.

Normally I can follow the "when in doubt, drain it out" method but we've been having a lot more snow & ice than usual and it took about 200 gallons of hot water to melt down to the drain plug last time

Thanks in advance...

 

[Bama Rambler]

Welcome to TFP.

First, I'd like to see a picture of that?

Now on to the problem at hand. They make an enzyme product for just this sort of thing. It's called Pool First Aid I believe. I would go by the local auto parts or industrial supply store and get some oil pigs and/or blankets and soak up as much as possible and then get some Pool first Aid and take care of the rest. It probably won't take much.

Chlorine will most likely oxidize it given enough time and quantity but it'll be much quicker and easier to use the pigs and enzymes.

 

[bridgman]

Great advice, thanks !

There isn't really that much -- maybe 30 quarter-sized patches on the surface rather than the 1 or 2 I usually get -- so even a few pieces of shop towel might be enough to get most of it. Things do tend to get dropped and spilled into the tub so having a bottle of Pool First Aid around seems like a good idea.

I'll take some better pictures but these should give an idea...

#1 - tub is built, deck under construction... note the nice new cedar colour


#2 - deck covered & filling tub for the first use, note tub is now grey (finishing the deck took longer than expected)


#3 - typical winter appearance although cell phone camera made it look a *bit* more dark and gloomy than usual

 

[bridgman]

this post disappeared then came back after I posted #5 to replace it... so removing this one to minimize duplication

 

[bridgman]

OK, that's weird... my post #4 just disappeared... let's try again.

When I got home tonight FC was 0.2, CC 0. I was glad to see the CC at 0 because it had been sticking around 0.2-0.4 the previous day. Assuming that concentrated Clorox regular bleach in Canada is 8.25% (??) I took the tub up to shock level just in case, we'll see what survives in the morning.

Here's a better pic of tub plus deck, taken last fall. The benches inside are at deck height so getting in and out is easy. The chimney only smokes when the fire is starting or damped down -- normally there's no smoke at all when it's burning hot.

 

[Patrick_B]

Well, this is certainly an interesting setup. Sorry you had the trouble, but I'm glad you posted so we could see it.
Really neat, and I like the seclusion implied there with the woods in the background. Nice.

Good advice from Bama, and I sure didn't know about the enzymes to help.

 

[Bama Rambler]

Thanks for posting the photos. I've heard about those heaters but never really seen one installed. It's an interesting concept.

 

[bridgman]

OK, test strip said that chlorine was 0 this morning, so added another ~14 oz of bleach. Will run some dilution tests tonight to see what concentration the bleach really is, but for now I added enough to be "in the ballpark" whether it turns out to be 6% or 8.25%. No sign of the creosote, water looks great, but guessing there are still lots of tiny bits of creosote in there that are too small to see. It'll be a race to see whether the chlorine finishes it off before I can lay hands on some enzymes.

Here's a less-depressing winter shot, taken this morning. You can see the "circulation system" hanging from a hook to the right of the tub.

I would have dug out a wider path to the tub but there's a few inches of ice hidden in the snow, left over from the last ice storm. It's easy to get through the ice with an axe or a 500,000 BTU propane torch but I don't like using either of those on my deck, and clearing the whole deck with hot water seems like something I'm not quite sufficiently obsessive to attempt. I should try to get rid of the ice on the path to the tub though...

 

[bridgman]

Roughly an hour after adding bleach the drop test says FC is 6.0, CC 0.4, so looks like the chlorine is still working away on something in the water. I'm still not seeing the initial FC levels I would expect from the amount of bleach I'm adding so need to do some testing there over the weekend. I just purchased the bleach last week but I guess it could have grown old on the Walmart shelves before I picked it up.

I have an unopened jug of 10.something percent chlorinating liquid (Purox), think I'll add another ~6ppm of that as well. No guarantee it's fresh either but at least it's different.

EDIT -- adding 6 oz of Purox took the levels to 13 ppm FC, <0.5 ppm CC (10ml sample this time), so at least the Purox is doing what I expect.

pH still 7.2 this morning. Following readings (for completeness only) are from a couple of days ago :

TA is a bit under 150, figure I'll leave it there for now unless I have a problem with pH creeping up. Since I don't have pump/jets/aeration and pH is on the low side I figured I didn't need to take the TA down with any urgency. CH is 170.

Thanks again for the help. I am surprised how well bleach seems to be taking care of the creosote. Think I'm having one of those Homer Simpson "Mmm, Chlorine, is there anything it can't do ?" moments.

 

[bridgman]

OK, just got home and happy to see that chlorine level is <not zero>, roughly 7 ppm. Picked up a new thermometer on the way home so looks like we're back in business. Found a couple of stores around Toronto that carry Pool First Aid so will try to pick some up next week.

Water temp is still at ~75F so should only take a couple of hours to heat up after I light a fire in the morning. Before anyone asks, yes a couple of people have built smoking chambers into their heater chimneys so they can smoke ribs and heat up the tub at the same time.

Hey, TFP already has a Snorkel smiley !!

 

[duraleigh]

I have been reading this thread a bit piecemeal.

What is Pool First Aid and what do you expect it to do for you?

 

[bridgman]

Pool First Aid seems to be an enzyme product (suggested in post #2) which may help to clean up accidental spills of <things that shouldn't be in pools or hot tubs> more quickly than just chlorine.

Since my circle of friends is more likely than the norm to put unusual things in hot tubs (the day after first use I spent the morning picking exploded firecracker bits off the bottom, for example), and since I wouldn't be surprised to find minnows or cooking oil from the turkey fryer (carried in on skin, not poured in directly I hope) in there one day, I figured that having a bottle of Pool First Aid handy might not be a totally bad idea.

No intention of using it as part of normal maintenance.

 

[bridgman]

Bah !!

Chlorine levels have been holding up nicely, so fired up the heater today and went for a dip. While I was in there, took the skimmer and reached under the benches looking for a couple of unidentified things I had seen on the bottom when the sun was "just so". Not only did I find a few chunks of smoked salmon and whitefish (appetizers last time my friends were over) but I also found the stainless steel bowl we were using as a serving dish. There was one big chunk I saw but didn't find with the skimmer yet, so either it's still down there or the chlorine is better at oxidizing smoked fish than I expected.

Apparently if you float the metal bowl in the water it keeps the smoked fish warm... until a "wave" washes over the side and sinks both the bowl and the food. One of my friends used to have a spa but got rid of it because "keeping it clean was too much work". At the time that didn't make sense to me, but I feel like I'm starting to understand now...

Did some dilution tests on the Clorox bleach and Purox liquid, btw, and AFAICS the "concentrated Clorox regular" is looking to be 6% not 8.25%. I'll run some similar tests with dichlor as a reference at some point, but if I measure based on 6% I seem to get more predictable results.

By the way, I didn't know how to put this into the signature line but I do have an Intex 637R filter/pump that I haul out sometimes when time permits. It just sits on the deck with the hoses draped over the edge of the tub -- only comes out a couple of times a year so hardly worth mentioning, although I did run it for an hour or so yesterday. The reason I don't use it more is that there's a leak somewhere in the pump/filter assy (pretty sure it's not in the hoses) so that after ~5 minutes the pump chamber fills up with air then I have to power off & bleed the air out. I have seen a couple of references to the 637R having a "sediment valve" but no idea what or where that is... if it exists and is open a bit I guess that would explain the symptoms.

EDIT -- did a bit more digging around and found that the larger pump/filter sets do have a separate sediment valve on the outside of the filter chamber at the bottom. You basically unscrew it and the filter housing empties, carrying out the sediment that didn't get stuck in the filter. AFAICS none of the smaller units (including my 1000 GPH model) have a sediment valve, but the text was copied and pasted across all the models anyways... and I have to look somewhere else for the leak.

 

[bridgman]

OK, finally caught the big chunk of fish

After some more paddling (I'm heating up the tub today) the fish and other debris ended up in the center of the tub. Getting it out was easier than I expected -- all it took was a leftover 6 foot length of 1-1/4" grey PVC conduit. I put the skimmer down on a bench inside the tub, covered the cut end of the conduit with my hand, then stuck the bell end of the conduit underwater near the fish.

When I took my hand off the top of the conduit water shot up into it (which I expected) then momentum carried the water right up to the top (which I didn't expect) so the entire length of the pipe was filled with water/debris/fish. Moved the bell end of the conduit over to the skimmer, took my hand off, and water/fish/debris flowed out into the skimmer. Took the skimmer out, gave it a flick of the wrist... presto, flying fish.

 

[Molson]

This thread is awesome.

 

[bridgman]

Woo hoo !! Finally figured out where the leak in the pump was coming from. One of the o-rings that sealed the hose-to-pump fittings got twisted when I put the hose on, but the twist was hidden under the hose clamp so I couldn't see it. Straightened out the o-ring, put the hose back on with a bit of grease so it wouldn't get caught again, tightened the clamps down again and (knock on wood) the air leak seems to be gone.

So I now have an occasional filter that runs long enough to be worth using:

Next step is to find some freeze-proof quick-detach fittings so I can plumb in a permanent suction and return, with enough separation to get decent circulation. Guess I don't have to worry about turnover with a 1000 GPH pump and a 680 gallon tub. I keep thinking there should be something I can cobble together using the filter cartridge and a submersible pump that I can leave in the tub (so it doesn't freeze) except when I'm using the tub or need to clean the filter.

EDIT -- just rinsed off the filter after running for a couple of hours. When you don't have to stop & bleed the pump every 5 minutes this thing does actually filter stuff out of the water. Maybe it will help with those #$%^@?!! mosquito larvae... but for that I guess I have to go learn about skimmers.