Flex seal liquid reef safe

Mike N

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I've done research about using flex seal inside my aquarium and everything I read points to it being reef safe after fully curing.

I plan on using it to coat magnets for DIY frag racks.

I guess I'm just looking for reassurance before putting it in the tank.
 

P-Dub

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I've done research about using flex seal inside my aquarium and everything I read points to it being reef safe after fully curing.

I plan on using it to coat magnets for DIY frag racks.

I guess I'm just looking for reassurance before putting it in the tank.
It says non-flammable and non-hazardous BUT it also says mildew resistant. The mildew inhibitors are the problem. Just coat the magnets with epoxy and you know it is safe.
 
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Mike N

Mike N

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It says non-flammable and non-hazardous BUT it also says mildew resistant. The mildew inhibitors are the problem. Just coat the magnets with epoxy and you know it is safe.
Yeah I did not initially see the mildew resistance part, thanks!
Too bad though, flex seal makes a nice, even and glossy finish. It was going to look so pretty lol.
Epoxy it is.
 

P-Dub

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Yeah I did not initially see the mildew resistance part, thanks!
Too bad though, flex seal makes a nice, even and glossy finish. It was going to look so pretty lol.
Epoxy it is.
We're here for you and your reef, Mike.
 

Larry L

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I wouldn't necessarily rule it out just because it says "mildew resistant" - all of the 100% silicone products commonly used to build glass aquariums also say they are "mildew resistant", because that's just the nature of silicone - no additives required. What you need to worry about is if there's anything that mentions FlexSeal having added mildew or mold inhibitors. It also depends on the product, e.g. the FlexSeal web site says that the FlexSeal Liquid is safe for use with potable water, but the FlexSeal spray is not. I'd try to find a product data sheet for whichever one you're planning to use.
 

P-Dub

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I wouldn't necessarily rule it out just because it says "mildew resistant" - all of the 100% silicone products commonly used to build glass aquariums also say they are "mildew resistant", because that's just the nature of silicone - no additives required. What you need to worry about is if there's anything that mentions FlexSeal having added mildew or mold inhibitors. It also depends on the product, e.g. the FlexSeal web site says that the FlexSeal Liquid is safe for use with potable water, but the FlexSeal spray is not. I'd try to find a product data sheet for whichever one you're planning to use.
The silicon used in aquarium manufacturing is specifically not mildew resistant making it safe for aquariums. Take for example any of GE's 100% silicone sealants, the only ones safe for use on aquariums are specifically not resistant to mildew and that is GE Silicone I or SES1200 and those are specifically not microbial/bacterial resistant. Stay away from any silicone that specifically states mildew/mold resistant. The nature of silicone is only slightly more resistant to mildew due to it being purely inorganic vs some other cualking/sealing materials. Just FYI...
 
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SeaJay

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The silicon used in aquarium manufacturing is specifically not mildew resistant making it safe for aquariums. Take for example any of GE's 100% silicone sealants, the only ones safe for use on aquariums are specifically not resistant to mildew and that is GE Silicone I or SES1200 and those are specifically not microbial/bacterial resistant. Stay away from any silicone that specifically states mildew/mold resistant. The nature of silicone is only slightly more resistant to mildew due to it being purely inorganic vs some other cualking/sealing materials. Just FYI...
There is an important distinction that must be made with the GE silicones. Ge silicone II says "10 year mold free". However GE silicone I still says "resists mold" if you get the clear tub and tile kind. The "all purpose" silicone 1 is the only one that says nothing about mold resistance. The big box stores, at least where I live, only carry the clear silicone 1 in the tub & tile version. I made the mistake of buying the clear silicone I only to get home and realize that it says resists mold on the label. I had to return it then go online and order the clear all purpose silicone I for in store pickup since they didn't carry it on the shelves.

I am considering using flex seal to line the seams in the bottom of a wood terrarium. I did apply pond shield, but I'm worried about cracks since I did not fiberglass reinforce the seams. I have researched and they insist that it's 100% safe for plants and animals including fish ponds, I just can't wrap my head around how that could be true of any liquid petroleum based product. However, lots of the plastics and rubbers that we use are petroleum based, so who knows. I will likely just silicone the corners for peace of mind.
 

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@SeaJay only 10% safe for plants and animals lol. Typo for sure.
BTW I used flex seal in the bottom of my bare bottom tank. So far so good. It has been used for ponds for many years so I don't mind being the guinea pig.
 

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@SeaJay only 10% safe for plants and animals lol. Typo for sure.
Yeah, I have a bad habit of proof reading my text AFTER I send it.


BTW I used flex seal in the bottom of my bare bottom tank. So far so good. It has been used for ponds for many years so I don't mind being the guinea pig.
The company says it's safe. Some hobbyists claim otherwise with no evidence to back it up, just preconceived notions.
 

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@SeaJay only 10% safe for plants and animals lol. Typo for sure.
BTW I used flex seal in the bottom of my bare bottom tank. So far so good. It has been used for ponds for many years so I don't mind being the guinea pig.

@SeaJay Did you ever have any issues after adding directly to the bottom of your display tank? My RODI top off water container has a leak and i was hoping to use some Flex Seal liquid to fix it.
 

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@SeaJay only 10% safe for plants and animals lol. Typo for sure.
BTW I used flex seal in the bottom of my bare bottom tank. So far so good. It has been used for ponds for many years so I don't mind being the guinea pig.
@Silent Did you ever have any issues after adding directly to the bottom of your display tank? My RODI top off water container has a leak and i was hoping to use some Flex Seal liquid to fix it.
 

Dr. Dendrostein

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I've done research about using flex seal inside my aquarium and everything I read points to it being reef safe after fully curing.

I plan on using it to coat magnets for DIY frag racks.

I guess I'm just looking for reassurance before putting it in the tank.
Also plasti-dip reef safe
 

Newbie4045

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No issues for me.
@Silent @Dr. Dendrostein Thanks for the replies! I ended up going with the Flex Seal liquid in the inside bottom of the container and Plasti-dip for the bottom outside.

How long did you guys let these things cure and air out after you used it? I poured the Flex Seal a couple of weeks ago, still smells a bit. Tried adding RODI water to the container and started reading TDS levels for a few days before i use it again and Ive seen TDS rise from 0 all the way to 14 within 2 days. I was waiting till it levels out and hopefully that means any chemicals will stop leaching out.
 

Silent

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I don't recall how long I left it to cure before I added water. A few weeks maybe. I let it cycle a long time using bottled bac and ammonia and ghost feed before adding fish and coral. Also carbon dose. If I recall it still smelled some when I added water but I had a glass top on the tank.
 

Newbie4045

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I don't recall how long I left it to cure before I added water. A few weeks maybe. I let it cycle a long time using bottled bac and ammonia and ghost feed before adding fish and coral. Also carbon dose. If I recall it still smelled some when I added water but I had a glass top on the tank.

Sounds good, thanks a lot! I will add water to the container and let it sit for a couple more weeks, stirring and changing the water so often to get rid of any chemicals. In the meantime I will just continue to use my 5 gallon bucket lol.
 

fnlyreefready

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I've done research about using flex seal inside my aquarium and everything I read points to it being reef safe after fully curing.

I plan on using it to coat magnets for DIY frag racks.

I guess I'm just looking for reassurance before putting it in the tank.
I know I’m super late but they claim their products are Fish safe

1E66F476-A37F-494A-B3B9-0BD6E6545DDC.png DEC173FB-7730-4EBA-A38C-C1E244002D2B.png
 

Silent

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I haven't had any problems yet. It did take a long time for my tank to stabilize but I am sure that is do to starting with dry rock and bare bottom.
 

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