dont do this!

[BichirKing]

for those who say silicone doesn't stick well to acrylic I'd love to have the help trying to peel it off ! I also have a 240g 8' tank made by the same person with a silicone fetish, I ended cutting it up as it wasn't water tight either.
luckily these were cheap and I'm going to use Weldon 40 on the outside seams.

 

[PYRU]

Thats a crap job doing silicone as well

 

[BichirKing]

its all over and inches thick in some spots. I'm amazed it still leaks.

 

[CarpCharacin]

The silicone won't seal properly on acrylic, it'll stick to some degree, but if you soak it in water, it should peel off.

 

[BichirKing]

The silicone won't seal properly on acrylic, it'll stick to some degree, but if you soak it in water, it should peel off.

I understand, that's why I put this up here as a don't do. its had water in it for about a month sitting outside and I top it off as it slowly weeps through the seam. that's why I'm sealing it externally as to avoid trying to peel it all out.

 

[ReApEr666]

paint scraper or putty knife should do the trick and give u something to hold onto better than just a razor blade to remove the bulk of it... no way around razor blades for the fine work then sandpaper to make sure the #40 sticks. will be a bit more benificial to try and get the glue on the inside although i have patched on the outside seams like u propose when all other efforts have failed.

 

[BichirKing]

I'm just worried that I wont be able to get it all out and make a proper surface for the Weldon 40. I tried razor blades and plastic scrapers last night but I don't have the time as its holding up my tank being up and running. my polys need their FINal home.

 

[ReApEr666]

I'm just worried that I wont be able to get it all out and make a proper surface for the Weldon 40. I tried razor blades and plastic scrapers last night but I don't have the time as its holding up my tank being up and running. my polys need their FINal home.

i know that feeling...been there many times.. best advice i can offer is to take the time to do it now best u can while its dry so it lasts for the long haul. Ive rushed and ended up regretting it later having to tear back down with fish inside. For outside patches u can run 1/4" material down the length of ur seam 2-3" wide and glue with #40... has worked well for me on the worst of seam repairs. Light sanding on both acrylic surfaces then wipe down with nail polish remover containing mild acetone and ur good for the glue. Patches like this are fairly easy with #40. put them down like a sticker to push out air and tape in place. u actually want them to be a bit "loose" for better adhesion. its easy to just push the glue right back out with clamps or weight.

 

[Oughtsix]

Get as much of the silicone off with a razor as you can then sand the acrylic. You are most likely going to sand and polish the acrylic once you are done welding the tank back together so you might as well start the sanding / polishing while it is apart (much easier than when the tank is together!).

I would start at about 1000 grit sand paper then 1500, then 2000, then Novus polish. If you do this for each acrylic sheet you will be pretty much assured that there is no silicone residue left on the surface.

I do not know if you want the weld surfaces polished out with the Novus polish when welding the tank??? I would think that you would want a little bit of roughness to the surface to get a good bite with the weldon... but I have never built an acrylic tank so take my advice for what it is worth. I HAVE done plenty of polishing on acrylic tanks though!

If it were me I would polish the whole acrylic sheet down to the fine Novus. Then mask off the non-contact points of the tank with masking tape and scuff the weld contact points of the acrylic with 1500 grit. The 1500 grit surface should give you a better bond than perfectly polished acrylic.

The only time silicone will stick really well to acrylic... is when you don't want it on the acrylic!

 

[BichirKing]

The only time silicone will stick really well to acrylic... is when you don't want it on the acrylic!

aint that the truth!

I have used the w40 on the tank seams and they have a finished surface and I have no concerns about it not being enough bite. I used the w40 and did the external patch and the sump is now holding water.
I cut the other tank up and will be reassembling it this summer. I have another 240 that this sump is used on that I spent way to much time polishing on for what it is(garage tank).