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Aqua Jon 10-18-2012 01:30 AM

Pic How To: Removing Plastic Rim & Cleaning Old Tank
So about two weeks ago, I decided I wanted a rimless tank. But all I had was the one I bought at the pet store with the black plastic rim around the top. Looked around for some advice, but couldn't be sure of what I read. So I decided to make it a learning experience. And learn I did. But in the interest of learning I took photos as I deconstructed and cleaned the old 2.5g tank. My hope is to help all you all out there looking to do the same, but who aren't confident enough to go through with it. Please learn from my mistake(s). This should be an easy visual DIY guide towards enjoying a rimless top style tank. No chemicals needed! Yay!

NOTE: Removing the rim can put your tank at risk for falling apart with the weight and pressure from the shear volume of water. If you are attempting this on a large tank, do your homework. Check silicone work and when in doubt reinforce your corners with bracing.

Razor Knife (with detachable blades or a loose blade as well)
Parent supervision or assistance for the young ones, cheesy I know, but being safe is better than first aid.
^ Start by scoring (scratching) the plastic from one end to the other. Move slow and careful, you want a good score line to follow. Continue to score the plastic following the same line until you break through. You may be able to separate the plastic as seen above. Then cut slowly with very light downward pressure, you don't want to break the glass.

! Warning !
^^^ DO NOT DO THIS! ^^^ You will break the glass using any object or prying motion!

See, it does break:

Cut away the front facing and back facing plastic so you can see the glass, as I did partly in the image with the screwdriver. Then use your finger to push from the bottom up in each corner to remove the rim, like so:
The plastic rim should come off relatively easy. If it does not, spend some more time removing the outer plastic with the knife.

Aqua Jon 10-18-2012 01:32 AM

Now time to remove the silicon around the rim.
I think it is best to leave some silicon in the corner for bracing purposes.
^ Use the knife at an angle flush to the glass to remove the silicon. It will come off in chunks at first.
^ Continue to shave the remaining layers of silicon until it is as clean as you like. Took me several passes to get clean, try going in different directions as well. Also now is a good time to use that free blade to shave from bottom to top for an extra angle to remove silicon from the glass.
^ Continue to shave off silicon or algae on the glass - most used tanks have a layer of algae or grime of some sort that the previous owner did not want to remove. With a fair amount of effort you can restore the tank to a like new state.
^ Rinse out the tank and hopefully your done. May take a little extra cleaning and another rinse. The hose adapter "pressure washer" made it easy without damaging the tank. I wouldn't use a powered one though.

Aqua Jon 10-18-2012 01:47 AM

Those pictures are huge! sorry about that :\ seem to have some issues resizing them on my end...

AbbeysDad 10-25-2012 07:58 AM

Clearly I must have missed something.
Why did you do this?
What purpose does it serve?

As you pointed out, it should be noted that removing the top rim of a glass aquarium should really NOT be done. In addition to providing a mount for a hood, the rim (and cross brace in larger tanks) provides a significant amount of structural support... And you broke the glass in the process!

I'm also surprised you would do this kind of work and post pics of the process with gravel still in the tank!

Tazman 10-25-2012 08:48 AM


This should never be attempted on any tank not designed specifically to be rimless. Rimless tanks are designed to offer significant structural support that on a regular tank is provided by the trim. The trim prevents undue pressure being placed on the seams of the tank and also prevents the tank from bowing somewhat.

It is ok to do this on tanks when you are replacing a broken trim but only for replacing the trim.

Aqua Jon 10-25-2012 11:32 AM

The tank is 2.5 gallons and the plastic rim has no structural support at that size, as I mentioned not to do this on tanks larger than this... Also what if you have a tank you are someone replacing the plastic since the original brace was damaged or old?! Now you can see and learn from my mistakes, as i have said, so it can be done confidently. The purpose was to show others how NOT to break the glass AND how to clean old tanks. I personally am recovering and converting the OLD tank (hence the gravel and mess it was! So critical without any foresight or comprehension). You can't show how to clean a tank if you start with a clean tank.....

However, I would like to see evidence of a flimsy plastic rim preventing bowing or undue stress. It is primarily a support for equipment being placed directly on top of the tank. If the equipment weight is not being distributed in a downward force then there is no force other than the weight of the water to break the silicon seal of the tank. Off the seal is not well done EVEN ON A RIM SUPPORTED TANK, it will burst or leak.
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AbbeysDad 10-25-2012 12:47 PM

Wrong. Plastic is pound for pound stronger than steel. That 'flimsy' plastic rim (your words not mine) offers substantial support in spite of what you think. I don't know the exact corner to corner tensile strength, but I know most men couldn't pull it apart!

I feel your post is a problem and I spoke up because it may encourage others to follow your lead and unnecessarily damage their aquarium (like you did). If you were replacing a damaged rim, I'd likely have let it go... but if you were replacing a damaged rim, you'd still remove the gravel first.

Aqua Jon 10-25-2012 02:42 PM

Since my purpose has been and continues to be to help. I will rewrite the entire post if we can find information proving one idea or the other. I read elsewhere that it is okay. But it's time to put some data behind it. The Internet isn't the most reliable source always, but I found some sites so far that give information on plastic strength. And will scour the Internet until I feel satisfied.

I really really wish you would read or re-read my entire post. I am trying to put up a tutorial TO PREVENT ANYONE ELSE FROM BREAKING THEIR TANK. I don't see why you keep tryin to paint me as someone putting up information that will cause others to break a tank. The inspiration to write this post was that I broke my own tank following someone else's directions. And if you read the bold red text I have in the first post..... You will hopefully understand that it says do not do like this, but instead like so....
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Aqua Jon 10-25-2012 02:46 PM

P.S. I'm not trying to revolutionize the aquarium, I am not trying to incite riots against plastic rim tanks. I am not trying to convince and persuade everyone or anyone to remove the plastic rim. BUT for those that do... Here is a way that works along with a picture of what happens when you don't do it that way. So that, for the last time, I can help spare anyone from cracking their tank.
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Tazman 10-25-2012 08:59 PM

Dear Mr X..(name left out)

Thank you for contacting United Pet Group regarding the tank trim on your 220g tank.
I have spoken to our manufacturing department and would like to inform you that you will require a new trim for the bottom of your tank.

All glass manufactured tanks require both a top and bottom trim to aid in the structural integrity of the glass. Tanks with trims are designed so that both trims offer structural support and we would never advise our customers or any person with a glass aquarium to remove this trim. Tanks that are designed rimless are made in such a way that the pressure exerted from the water and equipment on the tank is evenly distributed along all seams in the tank.

Thank you again for contacting United Pet Group (Marineland) and we look forward to offering support should you require it.

Yours sincerely

Catherine Dennis (Senior Technical consultant, United Pet Group)

Kind of sums it up really that the trims are needed unless the tank is designed rimless.

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