Bonding Acrylic to Glass

[cbm369]

Hi,

In the process of setting up my 55g sump/fuge for my 125g fowlr tank.

The 55g is a glass tank and because I already have some acrylic sheets, I thought of using them for my baffles in the sump/fuge.

Will silicone give a strong enough bond/seal on the acrylic baffles to the glass tank, or would it be best to use glass baffles?

TIA

[Saltydrip]

Good question. I'm in the same boat.

I have some thick lexan I was going to use but I decided to go to lowes today and just get glass cut.

[whitemarlin]

I used acrylic baffles in mine and my brothers 29g sumps both have been running 3 months with no problems. i don't see any reason that you shouldn't get a good bond.

[michaelr]

Same here my fuge has acrylic dividers

[Chuongj510]

I used silicone and haven't have a problem.

[sleepydoc]

Silicone bonds (very) well to glass, but not so well to acrylic. Try rubbing some acrylic off a piece of glass and then off a piece of acrylic. That said, it usually works fine for baffles. Even if there's a small leak, it doesn't matter much in a sump. You are expecting the water to flow from one section to the next anyway, right?

A couple of caveats/warnings. Several people have reported their glass sumps cracking, supposedly from acrylic baffles. There doesn't appear to be any definitive answer, but as near as I can tell, it is likely from a combination of factors.

First, some people wedge their baffles in fairly tight. This puts stress on the glass from the get-go and isn't necessary. The silicone will seal the seams. Second acrylic will absorb water over time and expand. The best data I've found on this is that it will expand about 0.3% over time. That's about 1/32" per foot; Cast acrylic is better than extruded. If a piece is already wedged in place and it expands, even a little bit, the stress may be enough to cause cracking.

I've talked to several people who have acrylic baffles in glass sumps that have been fine for years. I just made a sump and used acrylic baffles, leaving 1/16" on either side of the baffle. Just filling it with water, so I'll let you know in a few years how it works!

Glass is always safe, but more prone to breaking if it gets banged with a rock or something. 1/4 or 3/8" glass is stronger, but can be hard to find. I'd still leave a 1/16" gap with glass baffles. The silicone will easily cover it, and then you're safe.

[Magnetic Reaper]

you could probably use hot glue... works really well on both glass and acrylic/polycarbonates. i'm not sure how safe or durable it is in salt water, but i know you can get them as 100%silicon, though most brands are other polymers. i think they should generally be safe...

[JR's Reef]

You will be fine using it for baffles Ive have some done that be going for the last 6+yrs without any problem

[cbm369]

Thanks for the input everyone!

[Danzig]

Originally Posted by Chuongj510

I used silicone and haven't have a problem.

+1, silicone just holds the acrylic in place, works great.

[Saltydrip]

Hmmmm. How much does one piece of glass 1/4 in thick cost???

My thaught is that since I can get a tank from petco for $29 I'll have plenty of glass!!

How is tempered glass to cut?? Can it be scored and broke or does it need to Actualy be cut with a diamond saw like you would drill it? I can drill a tank. That has been done. But I have never tried to cut tempered glass. It it something to try??

[insanefishguy]

Taking a tank apart for glass is much harder than you would think! When I did it I had to smash a side(also much harder than you would think!!!) to get it started. When placing the baffles, I used a tiny dab of hot glue to keep them right where I wanted itthem and then ran my sillycone bead

[insanefishguy]

It was actually very entertaining hitting the tank with a 5lb sledge hammer and having it bounce back multiple times

[Saltydrip]

I made a tree frog tank from 2 10g tanks once. I broke the bottom out of the one tank and stacked it atop the other with a screen lid. It was cool. I could take the top tank off and get to the bottom of the tank with ease. I had a japanese maple growing in it with two common tree frogs. It was way cool.

[Saltydrip]

Lol... Totaly forgot the point of the story!!

It was unreal how hard it was to brake the glass out of the bottom of that tank!! I couldn't believe it!!

I see your point about getting the tanks apart. I'll make a call tomorrow about getting some cut.

[Airywhitesoul]

I got acrylic to adhere to glass with epoxy. Afterwards I silicones the joints. It was water tight for about a week and then it started diffusely leaking. I believe it was due to subtle differences in temperature contraction/expansion with the two different materials. Much like what others have said, it wouldn't have been a problem as the leak was very slow. However, one of the chambers held the water for my ato, so it needed to stay as freshwater. I ended up removing the baffles and replacing with glass.

[twelvejewelz]

do it once do it right , do it wrong do it twice or however the heck the saying goes lol. Glass to Glass and acrylic to acrylic is always the best bet, not saying it wont work but always do things right and the best possible way so you dont have to pay and do it over again. If it dosnt hold for some reason it will be a pain to take apart and do over..

[Magnetic Reaper]

Originally Posted by Saltydrip

Hmmmm. How much does one piece of glass 1/4 in thick cost???

My thaught is that since I can get a tank from petco for $29 I'll have plenty of glass!!

How is tempered glass to cut?? Can it be scored and broke or does it need to Actualy be cut with a diamond saw like you would drill it? I can drill a tank. That has been done. But I have never tried to cut tempered glass. It it something to try??

tempered is impossible to cut. as soon as you go trough the brittle outside layer, the whole thing blows up.

if it's done super gently then you get this
http://www.youtube.com/watch?v=qvRgklsm6so

or if you're not gentle
http://www.youtube.com/watch?v=Cw9tonCdFyc

take it from someone who tried cutting an old tempered patio door. i had no idea it was tempered and it shocked me

[larrypoe]

Originally Posted by Magnetic Reaper

tempered is impossible to cut. as soon as you go trough the brittle outside layer, the whole thing blows up.

if it's done super gently then you get this
http://www.youtube.com/watch?v=qvRgklsm6so

or if you're not gentle
http://www.youtube.com/watch?v=Cw9tonCdFyc

take it from someone who tried cutting an old tempered patio door. i had no idea it was tempered and it shocked me

coming from someone who worked in a window factory for 7yrs......I wouldnt say impossable.......more like "dont try this at home kids"

[Saltydrip]

I'll get glass cut.

[zigzag1]

I always do mine in glass for a glass tank. It's really been pretty cheap and easy to call a local glass company, place an order, and pick it up a few days later. I did this again recently for baffles for a new sump. I had (3) pieces appox. 10" x 17" and (1) 5" x 17" in 1/4" glass that cost just over $20 including tax. I don't remember the exact size, but they were for a 40 breeder. They were custom cut just to my specs and the edges were sanded/polished to not be dangerously sharp. Not really sure if that's a good price or not, but that's what I paid. JMTC & GL!

[Magnetic Reaper]

Originally Posted by larrypoe

coming from someone who worked in a window factory for 7yrs......I wouldnt say impossable.......more like "dont try this at home kids"

i suppose you could torch and cut, but i would hardly recommend doing that. the last thing once you blow up tempered glass is for it to be burning hot or half- tempered.

i am suddenly really tempted to spread the myth on the internet that novices can easily cut tempered glass by torching it...

[Toddrtrex]

All of the 6 sumps I have built over the years were glass tanks with acrylic baffles. The longest one was in service with me for 8 years, and to the best of my knowledge is still working (( sold it in June with I moved )).

The last one I built was a 20 long, with 1/4 inch acrylic baffles, I was able to pick it up by one of those baffles, the silicone held great. For me, I will always use acrylic baffles, find them a lot easier to work with.