For the last couple of days I have seen silicone questions being asked all over the DIY forum. I have a sealant rep who deals in Dow Corning, Pecora, and GE silicones. We are willing to do reasearch and find out what works and what doesnt. We are working on 999-A, 795, and GE Silpruf as we speak.

Please post what silicone you are wondering about and I will add it to the list.

Dow Corning 999-A: SAFE for glass to glass, glass to acrylic with no weight.
Dow Corning 795: SAFE for glass to glass, and PVC to glass as long as you rough up the surface of the PVC
GE SilPruf: NOT SAFE for any underwater application.
Dow Corning 732: I got no answer
RTV 103 & 108: SAFE for glass to glass.
3M's 5200 Marine Adhesive Sealant: NOT SAFE
DAP Aquarium Sealant: SAFE for all applications.
DAP Auto Marine Sealant: SAFE Is my guess, but I bet it's not very strong and you are using it at your own risk. Can't get a definite answer from my Rep.

I'm confused. GE-1 has been tried and tested for years, and is readily available and cheap. What's the relevance of other brands?

or is this more a strength/assembly thing and not a reef-safe thing?

It is gonna be both. It has to be strong and reef-safe. Some people might use something different than GE-1 and I thought it would be helpful to know what works and what wont.

Different silicones work better for different applications. DaveFason is doing a PVC to glass bond and they are trying to find out which is better to use, so I thought I would start a thread and share the information with other people and give them a chance to post what they use.

oic. carry on then.

Thank you!

Interesting thread I have in the past used silicon on glass to acrylic for overflows and such but never had good bonding and just ended up siliconing the crap out of stuff. So how strong is the bond on the 999-A to acrylic?

As long as it doesn't have to hold and weight it should work.

Really is no good way to bond acrylic to glass........

I'd be curious what the rep thinks about Dow Corning 732, I have only used it to build a few small tanks and put in sump dividers but I have a larger build in the planning stages and was hoping to do some nice thin black seams at up to 18-20" depth.

FWIW I had up to 6" of water level difference across an acrylic sump divider and the 732 held it just fine, and also one of the sumps cracked and I had to remove the dividers and they were in there GOOD. I obviously wouldn't assemble an acrylic tank with it but it seemed to adhere to the acrylic almost as good as the glass; I couldn't scrape it off with a razor and had to use a metal wire brush and silicone remover and still didn't get it all.

I added 732 to the list.

It is along the same lines as 795, but the adhesive property is not as strong.

RTV 108 (clear) or RTV 103 (Black)

Any RTV is safe for underwater use on glass to glass.

thanks nano-paul this will help a lot.
how do nominate for stickys.

NP,
I know it wasn't listed as a company your rep deals with but I am interested if 3M's 5200 Marine Adhesive Sealant is reef-safe. I have reviewed the MSDS but can't conclusively decide whether it is or isn't.

I am not interested if it will bond glass or not, just if it can be used in a reef-tank.


BTW, thanks for starting this thread and taking the time to look into this.

-Prof

No it wont be reef-safe. It is a polyurethane and will leach chemicals into your aquarium.

Only use if your fish are old and need lubrication.....

there went the sticky.

I fixed it.

Good read and thanks for doing all the lifting for this one. I appreciate it.

I think it'd be an excellent sticky thread.

What about DAP Aquarium Sealant? Is this Reef Safe?

Yep.


I agree!!!!!

Thankyou for the quick reply! Making my 10gal AIO frag tank atm.

Thanks for the info i have a 35gal Hex i want to redo.was wondering what to use.

ok so 999a vs 795


both are shore A 25 35
peel strength 20 32
cure in hours na 168 Hours to 336 Hours
Tear Strength = 25 ppi na
Tensile Strength = 325 psi = 45 psi




the big diffrence that i can see is that the 795 allows for greater movement in the joint. but other wise the 999 looks better for most applications. does this sound right or am i being stupid once again.

When I spoke with a Dow rep regarding the two he said 795 is what Disney uses on there 1000+ aquariums. Black only though no clear so 999 it is. For me at least.

dow makes 795 in more colors than they do 999a.

but no clear?

nano-paul, First, Thanks much for the effort you are putting forth for this. Now, Can you tell me which would be best for a glass to pvc application. Also it must be able to stick to silicone. I am putting in a pvc overflow and in the corners it will need to stick to the silicone that is already there. You only list two possibles, 795 and you are checking on the pvc part and Dow aquarium, safe for all, does this include my requirements? Thanks again. You are the man. Mark

Proper adhesion to PVC would only really matter if you wanted to build a tank with a PVC back or bottom, for doing an overflow anything reef safe is fine since the water pressure will actually be holding the overflow in place and the silicone doesn't have to do much.

Any color you want really.................................But clear.
That is according to a Dow rep so I hope i'm not passing on bad info.

795 glass to PVC is go!!! Dow says it bonds just fine as long as you rough up the PVC surface.


This would be correct.

good news then. Are you getting the same info on color choices?
I was told no clear on the 795...

That would be correct. No clear in 795. You have to go to the 999A.

daveFason's diy A.G.E. tank thread
http://www.nano-reef.com/forums/index.php?...217074&st=0

glass to pvc

One thing I really like about the 732 is that it has a cap and also the whole tip unscrews so when it has been sitting for several months with the seal punctured you just have to unscrew it, remove the plug of partially cured silicone from the tip and it is good as new.

...Just got some 795 in the mail today and it just has the regular cut off tip that you have to plug with a nail which never works very well Basically single use IMO, makes it way more expensive to use...

Used some 795 last night and It was fairly awesome to work with. I needed to Silicone a CVPC tube through a hole in the bottom of the tank and also silicone some generic plastic in the tank for a false wall. 795 worked great and made a really nice looking joint. I used black which looked more like really dark gray to me.

795 is the stickiest silicone I have ever used. I know that doesn't make sense but after you use 795 you'll understand what I'm talking about.

Now to wait out the 14 days.

Tagging along.

I think I wanna do a little 10g rimless ... with black silicone, I think.

I do not know which silicone bonds best with what.

So here is my question.

I would like to build a 100+ gal rimless aquarium (DIY) I am curious which silicone is best for this and what is the best way to apply it. I assume a large aquarium would need to be sliconed between the glass as well as have the bead in all corner joints.
How large would the silicone need to be flated out from the corner exaxtly?

This would be my first total DIY tank and planning has barely started on it. Need to start with the most basic components.

my first thought is to how thick the glass will be. there is a max depth the silicone will dry too. this may limit how you can use the silicone. as to which silicone, think this goes back to the argument about 999a vs. 795. i like 999a because it drys faster. hopefully nano-paul or one of the others will be able to weigh in though.

Glass thickness will be either 3/8 or 1/2 in glass

here are the data sheets for the two.

999a (two versions)
http://www2.dowcorning.com/DataFiles/090007c88023c52d.pdf
http://www.technologylk.com/images/pdf/Spec-CRL999a.pdf

795
http://www2.dowcorning.com/DataFiles/090007c88021ffb4.pdf
http://www.technologylk.com/images/pdf/Spec-CRL795.pdf


can not find the max cure depth for either, but would recomend having as little outside the butt joint as posable to improve said cure.

on a rimless biuld bigger is allways better to improve things like joint movement & panel deflection, so 1/2". but check aginst elos & ada tanks for comparision.

if i can rember were to find the info max cure depth i will add it as soon as i have it.

Ty bitts for the help here

I am curious why these are recommended but in their limitations they all say this.

Dow Corning 999-A Silicone Building
& Glazing Sealant is not recommended
for use in applications involving:
• Prolonged water immersion

we are talking about putting these in saltwater.. maybe its just a cover all for them but still seems like its saying it should not be used.

I didn't see this one on the list. Its for plastic sheets and other plastics. The only numbers on it are ges10.

^ Just bought some of this today. Anyone know?

nano paul
was wondering if you still had that video of the trucks that were siliconed together at the bumper.
would love to show it to my wife.

Any updates to this thread?

Well used the 999a in my exo build. I'm not quite the expert nano Paul, is but all I can say is damn. With in min while still tacky was able to hold the first panel with out assistance. Have lifted the tank by the exo.

what about GE SCS 1000 contractors 100% silicone? They sell it in my fish store and told me it's good to use but the container says it is not for underwater applications. Does anyone know? I want to use it because it comes in black and clear. Thanks.

Almost any 100% silicone is good. The deal with silicone and why none of the standard home commercial ones are listed as aquarium safe is because they don't want to be liable when you build an aquarium and pop a seam.

If they sell it at your LFS odds are they have used it and its safe (no saying LFS are the gospel on this but I would hope they have done a lil bit of research)

I have used GE silicone II with good results for reference.

Is this stuff ok? I was so confused about all the silicone.. Lol. I ended up paying out the a$$ for marineland silicone from the pet store. Maybe pics of each type of safe sealant would help in this thread as well. Anyhow below is the link to the one I'm wondering about. Thanks for the help.

http://m.canadiantire.ca/mt/www.canadianti...r.jsp?locale=en

Not true. Almost all silicone is labeled 100% silicone but is not really 100%. Most sold for the home repair/construction market has mold/bacteria inhibitors. That is really what makes them no good for aquarium use. Know what the other tiny % is all about..

Also what are you using it for?? Regular aquarium silicone is usually only good for glass to glass bonding and will not properly adhere to Acrylic over the long run.

GE Silicon II -- is generally not recommended for aquarium use (mold/bacteria inhibitors). Try and find GE Silicon I -- instead. Some Home Depot's and Lowes sell GE Silicon I -- but not all, depends on your location.

Now you had to say that.. so I went and read every word on my tube and there is no mold inhibitors on the GE Silicone II that i have. The ones that have the mold inhibitors etc are the ones that are kitchen/bath rated. I definately checked that prior to purchasing this product but rechecked to be 100% certain.

Moral of the story is know what your buying and which parts of what your buying make it safe or unsafe in this case.

from what i remember hd & lowes selling GE II only instead of both, as a corporate wide change.


the dow 999a is like 12 -14 online & bomb proof.