160 Gal Acrylic Restoration

  • #1
Hey everyone,

This is my first post and I am fairly new to the hobby, but I've jumped in feet first. Recently I came across a 160 gallon acrylic tank. Seeing the tank held water, I purchased it(for a great price!) in hopes of restoring it. Unfortunately I made a huge mistake. When I got it home I immediately found a level piece of concrete and began filling. The mistake was that the concrete had a small valley in it near the front center of the tank, which resulted in a split seam. Now I have to repair it before I move forward with sanding and buffing.

My question is if anyone has experience in doing a repair like this, and if there is any advice you would give someone attempting this. I have thoroughly cleaned the tank and area where the split is. Also, I have a tube of weld on 16 on the way.

My plan is to first use masking tape or something similar to block the weld on from getting all over the acrylic and making it foggy. This will depend on what does not react with the weld on.

Next I will use some toothpicks to spread the seam enough to get the weld on in the seam. During application I will remove them one by one while trying the spread the solvent in each crevice.

Lastly, I will use a few ratcheted tie downs to pull the acrylic together and let set overnight.

Any advice or pointers would be greatly appreciated!
  • #2
Make sure any products you use are aquarium safe! Fish are extremely sensitive to chemicals. part 1 silicone usually will do.
  • Thread Starter
  • #3
The split is nearly 8 inches in length. I believe the weld on will not be toxic after it cures. I do plan on resealing the entire aquarium with silicone.

The weld on came in today. I am going to attempt the bond tonight and let set for 12hrs, then reseal with silicone.
  • Thread Starter
  • #4
Aquarium is holding water for nearly a week now. Turns out the acrylic itself had a bit of a bow to it where it split. Decided against the silicone since it won't adhere very well. Also reattached the center brace. Next up is to sand and polish. Then onto building the stand and setting up an oversized sump and refugium in the 75 gal I just picked up.
  • #5
This is amazing and you're living the dream, my dream, this is so cool and inspiring.

Question - how easy are these things to scratch? And how hard to buff out?

Also, cat.
  • #6
Silicone doesn't stick well at all to acrylic plastic. In order to make it work at all you have to roughen the plastic up with sandpaper until it's foggy.

But even then there's no chemical adhesion.

You get a mechanical rubber seal. With positive pressure because you have water inside the tank it could probably hold. Applied on the outside of the tank there is no chance.

Acrylic tanks are made not by gluing, but by solvent welding. The solvent actually melts the plastic, and when you stick the two pieces together, and it hardens, you have one solid piece. An acrylic aquarium is one single piece if done correctly.

Any person who thinks you can fix an acrylic aquarium with silicone should try this test. Clean a drinking glass and put one spot of silicone on the glass and sit it on your aquarium overnight. Clean that spot really well so you're not just putting silicone over algae and water.

Anyhow in the morning you will pull that glass right off your aquarium with no effort at all but the silicone will stick to the glass tenaciously and you will be picking it off with your fingernails for 30 minutes.
  • Thread Starter
  • #7
That's what I read about the silicone, so decided against it. Seems I'm set since the solvent worked.

As far as the acrylic scratching and buffing goes, this is my first acrylic aquarium so it's a bit of a learning process. I've heard they scratch quite easily.

Luckily for me, my family owns a Hot Tub retail store so I have quite a bit of experience repairing scratches and large dents in acrylic hot tubs. It's really just a matter of starting with abrasive wet/dry sand paper and working through to very fine. I typically go through 5 stages for the worst scratches. Lastly, a quality rubbing compound and buffer restores the shine. For really minor surface scratches the rubbing compound or 2500 grit sand paper then rubbing compound works.

Hopefully this process works with the aquarium!

Thanks for the replies everyone. I will keep updating as I proceed through the build.
  • #8
Well good luck, and I don't have to tell you not to let your buffing wheel get too hot.

I've never owned an acrylic fish tank although I do have acrylic Lids on some of my glass tanks.

But I have buffed out motorcycle windshields from plexiglass and lexan, with about the same procedures.

One thing they say about acrylic Plastics is not to leave them out in the sun because they weaken quickly from ultraviolet rays.

Similarly they tell you not to leave a glass aquarium out because the silicone suffers from cold temperatures.

I guess everything has its disadvantages.

I've been waiting for years for people to make aquariums in glass without seams. Just like a giant CorningWare baking dish. The problem is you can never get it flat enough to look as good.
  • Thread Starter
  • #9
I'm going all hand sand until the buffing compound. I have the tank in the garage now and had it covered when it was out back. Definitely aware of heating and cooling effects on acrylic.

I have 5 500-1000 gal used hot tubs right now that we need to take to the dump. I keep joking I'm going to seal them up and make a huge koi pond.

Similar Aquarium Threads



Top Bottom