Sealed sump pit getting moldy -

[ERD50]

The home we moved into has a finished basement, so I'm rather paranoid about flooding and have taken a belt, suspenders and another belt approach to our sump pumps and pit.

BACKGROUND INFO, skip if you want....
The original set-up was pretty good, a 3/4 HP good quality pump and a WatchDog brand backup pump with backup battery. I also have a 12V/120V inverter that I can use in an emergency to power a pump or recharge the backup battery. Because the radon measured just over the limit, the sellers put in a mitigation system (vent fan pulling from under the concrete floor), and a sealed cover was put over the sump pit. OK.

Drainage is pretty good around the house, and the ground water level must be fairly low, as the pump doesn't run at all until we get some rain. That main pump is large, which is good if we got some really hard rain, but for the normal occasional trickle into the pump during normal rain, it runs a very short cycle, like 5 seconds, because it pumps so fast. The float is attached and isn't really adjustable.

To resolve this, I bought a small 1/6th HP pump, added that with the external float switch set lower than the main pump. That runs for ~ 30 seconds to drain the pit. I don't think the 3/4 HP pump has come on even once since I installed the smaller pump (other than me testing it), so that's saving wear/tear on the 3/4 pump. And since the 1/6th HP pump was pretty cheap, I bought a spare, for a quick swap out if needed.

It was difficult to remove and replace the sealed cover to do any routine maintenance/checks/inspection (required unscrewing a bunch of screws, and re-caulking a panel). And I would have to chop it up to make room for teeing in the added 1/6HP pump, there wouldn't be much left. [End of BACK-GROUND INFO]

To provide better access, I removed the plastic radon cover seal, and built a plywood and 2x2 box around the whole thing, ~ 2'x2'x2' with latches on the front side. A sealed plexi window ~ 6x10 so I can see inside w/o even removing the latch. Sealed up, but just unlatch the front and I have good access to everything.

The problem I'm having now after about a year is that I've noticed a bit of a musty smell in the sump closet recently. This is winter, so it's dry air. I opened the latch, and I there is some mold/mildew building up on the inside walls of this cover box. It's exposed 24/7 to the water in the pit. I think I'll just try washing it down with vinegar, maybe some bleach, and then painting the insides of the box with some anti-mildew paint?

I can't ventilate it, that defeats the purpose of having it sealed for radon. And I don't see any practical way of sealing the pit from the box in some other way.

Any other ideas?

TIA-ERD50

 

[Sunset]

Couldn't you just replace the original radon cover seal with a plexiglass one sealed in place (remove the wood box). That way you can look and of course would need to cut out the caulking to open it, but that should really be a rare event.

 

[ERD50]

Couldn't you just replace the original radon cover seal with a plexiglass one sealed in place (remove the wood box). That way you can look and of course would need to cut out the caulking to open it, but that should really be a rare event.

Not a rare event. I reach in to trip the float to test each pump every couple months, and when a big storm is predicted.

I may post a picture later. With three pumps, the three pipes come up out of the pit, and are teed (Wy-d actually) about a foot above the floor. This was all done intentionally, so that most of the connections are at easy reach. I have flex connections placed such that it is very easy to remove/replace any of the pumps w/o disturbing the others.. And each has its own support so they don't 'walk' around and interfere with a float (that happened at the old place).

I really wanted to minimize the effort/time to replace a pump, in case it happens during an emergency. That big open front gives me access to everything by just unlatching. Every connection is the same size wrench.

Another advantage of the box - if any connection started leaking and spraying water out, it is contained by the box. I have a water alarm, and extended some sensor wires around the perimeter of the box, so any leak would also cause an alarm. If I just had a plexi seal, those connections would be exposed.

-ERD50

 

[Keim]

Perhaps placing a dehumidifier nearby would help.

 

[ERD50]

Perhaps placing a dehumidifier nearby would help.

No. It's sealed from the outside (for radon). I'd have to put a dehumidifier *inside*, but that's not practical.

-ERD50

 

[Keim]

No. It's sealed from the outside (for radon). I'd have to put a dehumidifier *inside*, but that's not practical.

-ERD50

Agreed. But, clearly it's not an airtight enclosure or the musty smell wouldn't be escaping into the larger sump closet.

 

[ERD50]

Agreed. But, clearly it's not an airtight enclosure or the musty smell wouldn't be escaping into the larger sump closet.

Sure, it's not hermetically sealed. And the closet is closed, so that's going to concentrate it.

It's sealed enough that the water sitting in the pit is going to raise the humidity. I just remembered, I should put a humidistat down there to check.

-ERD50

 

[Sunset]

So far, given your complex arrangement, it seems the answer is your idea of diluted bleach spraying and then painting with mold resistant paint (outdoor glossy paint ?) and then maybe once per year spray with diluted bleach again.

 

[Jerry1]

Couldn't you just replace the original radon cover seal with a plexiglass one sealed in place (remove the wood box). That way you can look and of course would need to cut out the caulking to open it, but that should really be a rare event.

Not a rare event. I reach in to trip the float to test each pump every couple months, and when a big storm is predicted.

You could install a pipe/hose so that you can run water into the pit in order to test it instead of manually tripping the float.

 

[JoeWras]

To provide better access, I removed the plastic radon cover seal, and built a plywood and 2x2 box around the whole thing, ~ 2'x2'x2' with latches on the front side.

....

I think I'll just try washing it down with vinegar, maybe some bleach, and then painting the insides of the box with some anti-mildew paint?

I'm gathering from the quoted above, that the box was not painted? If so, there's your problem. Mold loves wood, even pressure treated wood in some cases. (And it likes paper even more, but I digress.)

So I agree with your proposal, and Sunset's endorsement. Clean it, paint it, maintain it.

For cleaning, use something first that kills spores, then you can hit it with bleach, then you dry it and paint. Otherwise, replace the wood.

In our disaster work, we pretty much replace all drywall and plywood showing mold. The fungi set deep roots of spores, so we get it out.

It is funny you tell this story, ERD50, because on my volunteer maintenance gig, we have a house in the woods that was "smelling musty." I couldn't figure it out. Everyone, including myself, thought it was the crawlspace under.

Turns out they built a closet for the water heater. But this closet was accessible only by a screwed on panel. Out of site, out of mind. When we got around to opening it up, we saw that the heater drip/leak pan was full, and draining out under the house. Looks like it was doing this for years. This dead space had high humidity. The drywall paper was full of green mold. The colonies were partying it up. We ripped it all out. Party over.

 

[Sunset]

.....
So I agree with your proposal, and Sunset's endorsement. Clean it, paint it, maintain it.

For cleaning, use something first that kills spores, then you can hit it with bleach, then you dry it and paint. Otherwise, replace the wood.

.........

Today, I'm learning a lot.
You post made me look as I thought bleach was a great killer, but it won't kill spores or go deep.

Turns out full strength vinegar or hydrogen peroxide 3%(+) is a good killer of mold spores, etc.

There are a bunch of others too I read at: https://www.bobvila.com/articles/what-kills-mold/

 

[ERD50]

I'm gathering from the quoted above, that the box was not painted? If so, there's your problem. Mold loves wood, even pressure treated wood in some cases. (And it likes paper even more, but I digress.)

So I agree with your proposal, and Sunset's endorsement. Clean it, paint it, maintain it.

For cleaning, use something first that kills spores, then you can hit it with bleach, then you dry it and paint. Otherwise, replace the wood.

In our disaster work, we pretty much replace all drywall and plywood showing mold. The fungi set deep roots of spores, so we get it out. ... .

Right, not painted. I had thought about that at the time, but really didn't think about how much the humidity would build up in there.

I'll do a search on spore killing stuff - is there something you've used for that?


ooops, cross posted with Sunset...

-ERD50

 

[JoeWras]

I'll do a search on spore killing stuff - is there something you've used for that?

-ERD50

We use "Shockwave," a commercial product available on Amazon. You have to mix it.

However, a product that is pre-mixed in a convenient sprayer for small jobs is something like "Mold Armor." This has at least one of the active ingredients that Shockwave has, if not both. The name is too long, something like Alky dimethl benzy ammonium chloride. Chemical engineers are cringing at my naming.

 

[ERD50]

We use "Shockwave," a commercial product available on Amazon. You have to mix it.

However, a product that is pre-mixed in a convenient sprayer for small jobs is something like "Mold Armor." This has at least one of the active ingredients that Shockwave has, if not both. The name is too long, something like Alky dimethl benzy ammonium chloride. Chemical engineers are cringing at my naming.

Thanks, local Home Depot carries the "Mold Armor", so I'll get that, and then look into the best anti-mold paints (I recall there is an additive to use, to make it even stronger).

PS a quick search says Sodium hypochlorite is the main active ingredient in Mold Armor
PPS for Shockwave, it seems to be Quaternary Ammonium ( but that's a 'common name, I see an example is: Tetramethylammonium - that's a mouthful, but you probably don't want it in your mouth!)

-ERD50

 

[aja8888]

Thanks, local Home Depot carries the "Mold Armor", so I'll get that, and then look into the best anti-mold paints (I recall there is an additive to use, to make it even stronger).

PS a quick search says Sodium hypochlorite is the main active ingredient in Mold Armor
PPS for Shockwave, it seems to be Quaternary Ammonium ( but that's a 'common name, I see an example is: Tetramethylammonium - that's a mouthful, but you probably don't want it in your mouth!)

-ERD50

Isn't Sodium Hypochlorite (NaOCl) just bleach (undiluted of course)?

 

[ERD50]

Isn't Sodium Hypochlorite (NaOCl) just bleach (undiluted of course)?

I was kinda thinking that sounded familiar, but yes, you are right.

-ERD50

 

[Keim]

We have used Kilz primer with good results.

 

[JoeWras]

Isn't Sodium Hypochlorite (NaOCl) just bleach (undiluted of course)?

LOL! After looking around on Home Depot's site, I see there are two versions. One with the ingredient that Shockwave uses, and the other just being expensive bleach.

THIS is the one I'm talking about: https://www.homedepot.com/p/Mold-Ar...and-Disinfectant-Spray-Bottle-FG552/205143478

You can always start with or follow up with cheap bleach too.

 

[JoeWras]

We have used Kilz primer with good results.

Me too. I used to use the oil based stuff, but I think the water base is good enough.

 

[CaptTom]

Just consider the effects vinegar or Hydrogen Peroxide will have on any metal, and bleach will have on any rubber, in your pumps and fittings.

 

[JoeWras]

Just consider the effects vinegar or Hydrogen Peroxide will have on any metal, and bleach will have on any rubber, in your pumps and fittings.

I'm pretty sure OP will take the box off and use the product away from the pit. Well, at least I hope so!

 

[ERD50]

LOL! After looking around on Home Depot's site, I see there are two versions. One with the ingredient that Shockwave uses, and the other just being expensive bleach.

THIS is the one I'm talking about: https://www.homedepot.com/p/Mold-Ar...and-Disinfectant-Spray-Bottle-FG552/205143478

You can always start with or follow up with cheap bleach too.

Thanks, and here's the ingredient list (scroll down):

https://www.barringredients.com/brands/mold-armor?id=fg552

-ERD50

 

[ERD50]

I'm pretty sure OP will take the box off and use the product away from the pit. Well, at least I hope so!

Well, that's going to be 'fun'.

The front comes off with latches (super easy), and I designed the top to be pretty easy to remove (camper tape seal and screws - split so I could have the outlet pipe come through w/o 'trapping' it).

But the box itself fits diagonally into the corner (that's how the small closet was made, so that's about the only way I could fit it), and I had to assemble some of it outside the closet, then drop it in place. Some of those screws holding the box together are too close to the wall to get to when it is in place. I can take it out the way it came, but I also sealed the bottom 2x4s to the floor after I got it in place (might be caulk, but I think it's actually construction adhesive). So cutting that may or may not be a chore.

I might just do some vinegar clean-up for now, wait for a dry spell, and remove the pumps and clean/paint it in place. Removing the pumps won't be too hard, they were designed to be easy to replace.

Sure wish I would have handled this at the start! I did think about it, but not enough! Maybe someday, when I'm older and wiser (time's running out for that!)

-ERD50

 

[JoeWras]

Thanks, and here's the ingredient list (scroll down):

https://www.barringredients.com/brands/mold-armor?id=fg552

-ERD50

Yeah, yeah. That's it. Those "quaternary ammonium" inhibitors are what Shockwave uses.

In the classes we had, they basically said these kind of treatments are better because they don't tear up the substrate like bleach. We also don't scrub anymore. It is just gently wipe and apply. This is supposed to help avoid spreading it all over on stuff you don't need to get it on. The future inhibitor ingredients are supposed to be important.

Advice is changing all the time. First class I had 5 years ago was all about bleach. Now it is this.

 

[Sunset]

Just consider the effects vinegar or Hydrogen Peroxide will have on any metal, and bleach will have on any rubber, in your pumps and fittings.

OP could rinse off the pumps after spraying, or even cover them with a plastic garbage bag down in the hole before spraying.