Uncured Silicon ( expired ) toxicity for fish, and potential encapsulation

[fishmangomod]

I am creating an up-stream fountain for a fish pond. This upper tier is a concrete planter that I have reinforced with epoxy and fiber. It will house gravel and reeds, and has a spillway down into the pond.

I used an a tube of ASI Aquarium sealant that is not curing. It was unopened, but has expired. I am having significant issues removing it - it has a consistency between vaseline and rubber cement, and even on smooth epoxy leaves a slight film.

I will continue to manually clean up the silicone, and use some sort of solvent as a final pass. After cleaning off the solvent and air drying, I then plan to encapsulate with a final coat Epoxy ( if it will stick ) and then with liquid rubber. How dangerous to the fish is this uncured silicon? Will the leeching polymers be caught up in the reeds and other filters? Will they pose a risk to the fish in the pond?

Trying to decide if I should just start over with the fountain. Any help appreciated.

 

[smitten with ocean life]

@UncommonSense

 

[UncommonSense]

I am creating an up-stream fountain for a fish pond. This upper tier is a concrete planter that I have reinforced with epoxy and fiber. It will house gravel and reeds, and has a spillway down into the pond.

Cool! I’m doing a similar system for a client at the moment, I opted to use 5-6’ wide strips of 6mil UV resistant coated 24mil RPE pond liner to make my spillways, though! — could that be a potential solution? (You simply fold a pleat or pleats into a flat sheet to make it form a corner or curved spillway)

https://www.justliners.com/Merchant...2&Session_ID=c02d46a3d32503b46f074d1e5c80874a

I used an a tube of ASI Aquarium sealant that is not curing. It was unopened, but has expired. I am having significant issues removing it - it has a consistency between vaseline and rubber cement, and even on smooth epoxy leaves a slight film.

Interesting! I’ve never used an expired tube, but I’ve also never heard of this issue!

— How many days ago did you apply the silicone?
— How thick of a bead?
— rough average work area temps and humidity?


RTV (Room Temperature Vulcanizing) silicone, like ASI aquarium silicone sealant products actually rely on ambient humidity to cure! — very low ambient humidity will slow curing, spraying with water will speed curing!

I will continue to manually clean up the silicone, and use some sort of solvent as a final pass.

Try a metal putty knife, then some cheap sandpaper if you have an electric sander (you’ll eat through sandpaper fast, but it will get into the low spots that a metal scraper can’t…)

For solvents? I’m not sure which epoxy you’re using, but the likes of Methyl Ethyl Ketone (MEK; use proper safety equipment!) will do some of the heavy lifting for you with thorough scrubbing (use steel wool or a rough Brillo pad), assuming the epoxy underneath can handle such an agressive solvent…

How dangerous to the fish is this uncured silicon? Will the leeching polymers be caught up in the reeds and other filters? Will they pose a risk to the fish in the pond?

ASI 502 aquarium silicone sealant is what I looked up the MSDS on last; it is <=9% petroleum distillates.

So, it can have a maximum of <28ml of petroleum distillates per-tube… these off-gas to atmosphere over time… The longer you wait, the more gasses off…

Let’s be frugal and assume this is a 1,000L (258g) pond/plant filter system… that’s less than 28ppm petroleum distillates in the system, assuming you inject the entire 10.2oz tube of silicone straight into the water!


TLDR: I wouldn’t call this ideal, but I can’t imagine that you’re going to notice any appreciable change to livestock health from this small amount of silicone!

Trying to decide if I should just start over with the fountain. Any help appreciated.

It will be a lot of work to scrape the half-cured silicone off… either give it more cure time then scrape, redo the seal in a larger area around it, or just go for something like the above pond liner idea for your spillway!

 

[Randy Holmes-Farley Verified Community Expert]

I do not think this residue is a high risk.

 

[fishmangomod]

Cool! I’m doing a similar system for a client at the moment, I opted to use 5-6’ wide strips of 6mil UV resistant coated 24mil RPE pond liner to make my spillways, though! — could that be a potential solution? (You simply fold a pleat or pleats into a flat sheet to make it form a corner or curved spillway)

Yes, I could definitely go that route, although I'm hesitant to put even more money into this project. Pond liner is way expensive! If I can solve it with some elbow grease, I'm going to go that route.

Post a pic of your spillways? I'm curious to see how you did them!

Interesting! I’ve never used an expired tube, but I’ve also never heard of this issue!

It is definitely the tube, and not the local conditions. I have the open tube sitting next to me by my desk, and the silicon on the tip still hasn't dried. I used a new tube two days ago, and the new tube is working great.

Edit: This is the second time this year I have used an expired product leading to critical failure. I had an issue with some wood glue I was using as well, but figured it didn't matter. I was incorrect there too. :( Might have learned my lesson with this silicone tube though. It really cost me FAR more in time and stress than just waiting for a new tube to arrive in the mail.

Try a metal putty knife, then some cheap sandpaper if you have an electric sander (you’ll eat through sandpaper fast, but it will get into the low spots that a metal scraper can’t…)

This is what I ended up doing. I got super aggressive with the sander - and it did gum up a lot of sheets, but wasn't as bad as I thought it would be. It was frustrating have to get rid of a lot of epoxy ( my earlier epoxy pours were very uneven "learning experiments" so to get it smooth meant getting rid of a lot of material, but I'm glad I did.

The solvents would make the material more gummy, which helped to remove it in some places, but physical force ended up being easier I think.

TLDR: I wouldn’t call this ideal, but I can’t imagine that you’re going to notice any appreciable change to livestock health from this small amount of silicone!

Thanks, this is really helpful - it takes a lot of worry off of my mind :)

I do not think this residue is a high risk.

Thank you so much. I'm not in anyway an expert on fish, and hearing this makes me feel much better.

 

[UncommonSense]

Post a pic of your spillways? I'm curious to see how you did them!

Still an ugly work in progress, nothing’s finished out yet as I tested various aspects of the system...

Left spillway actually drains from the grow area, right spillway is a fake grow area drain that runs 5-6X the flow rate!

The pond itself benefits from the high flow, the grow area benefits from low flow… Hence splitting the pump to two outlets, and restricting one!

The grow area drain spillway is a strip of 30mil RPE/UV pond liner laid under the grow area liner, over the low point weir in the grow area… grow area liner is siliconed down on top of spillway liner where they overlap! — non-woven geo textile fabric underlayment for every liner!

 

[fishmangomod]

This looks great. Are those flagstones you are using for the spillway?

 

[UncommonSense]

This looks great. Are those flagstones you are using for the spillway?

Thank you!

They are, the spillways are still subject to change… but, if the client decides they like the “stair step” waterfalls that are currently there, I’ll cut the flagstones to fit much nicer with my tile saw, then concrete then in so water cant channel around/under them!

 

[fishmangomod]

My project is a much smaller scale. We have a 3x3 above ground concrete pond. I think it was originally a massive planter. In that vein, this is another planter, the same width, that will rest on the edge of the pond. It will be filled up with gravel and then reeds, with water coming in from the bottom, then going over the spillway down into the pond. We originally did this to cool things down a bit in the summer, which it did a good job of. I also have added some small misters we turn on when it gets really ugly temperature wise. My wife found that the reeds were doing a very good job of filtering ( nitrates maybe? the chemistry isn't something I know about ).

I created one of these a few years ago with a similar method, but I hand crafted the spillway out of copper. This time I salvaged one from another fountain. This planter is GFRC, and I added additional layers of fiberglass and epoxy inside. The brown at the bottom is me experimenting with thickening the epoxy with sawdust. I wanted to be able to smear it up on the edges more like a putty. I think the wood cooked from the heat, creating that dark chocolate color. It also hardened MUCH faster than expected, like in minutes instead of hours.

I still need to touch up the gap around the spillway, and I've decided to resurface the planter with a new concrete texture. I originally liked the cracked, whitish concrete, but now it just looks messy to me.