This all happened over a year ago, but I realize how many people this could help, so I'm posting here hoping someone can benefit from it!
My 140gallon, 150x60x60 rimless tank was all set up. Plumbing installed, stand built, 400+lb aquarium moved onto the stand...
More than 600 POUNDS of hardscape was added (Manten Stone from Aqua Rocks Colorado). The largest rock required two people to lift and place, as it was over 120lbs alone. I then scaped the tank very carefully, glued everything together with superglue and paper towel. I filled the tank to start the Dark Start cycle.
Then I noticed some superglue dried on the front panel. No problem, let me just grab my sponge:
It turns out, many sponges have aluminum oxide coatings on the scrubby side.
Which is harder than low-iron "starfire" glass that most rimless aquariums are made out of. Which means it will permanently scratch it.
After a quick scrub, my brand new dream aquarium had a 2" patch of VERY noticeable scratches:
Oh no.
OH NO. This tank was expensive, the rocks were expensive, it took 4 strong dudes to lift it into place... and I just permanently and majorly scratched it BEFORE IT WAS EVEN PLANTED.
I started researching everything online, and what I saw was very disheartening. 6/10 people say there is no fix, and to either live with it or get a new tank. 2/10 people say that if the scratches are fairly shallow (fingernail can't really catch in the scratch) then you might be able to "sand" or "buff" it with Cerium Oxide to get them out. But, everyone insists the tank MUST be on it's side to do this, it will make a mess, you can't have hardscape inside, etc.
Cerium Oxide doesn't appear to be very toxic, certainly not in weak, diluted solutions. I decided to drain the tank:
Cover the ENTIRE hardscape in as many towels and old t-shirts (the cerium oxide did wash out) as my girl would allow, and even form a watertight packing tape barrier on the front panel where the oxide solution would run down towards the substrate (worked AMAZINGLY well):
I used this Cerium Oxide with this Glass Polishing Wheel on my drill, set to Gear 2 (fastest).
I made a separate solution of RO water and cerium oxide in a squirt bottle to keep the pad hydrated/cool/filled with cerium oxide. Then, I got to work:
After 1.5 hours of nonstop pressure and buffing, I started to see a difference. My arms were killing me.
After 4 hours, the patch of scratches looked like this:
The tape/towel trick to keep the solution from reaching my substrate/bottom worked perfectly (note how there is no solution running below the taped towel):
Finally, after over 8 hours of constant pressure, overheating the drill and the glass (I let it cool frequently), spraying Cerium Oxide around the tank and my room, I was rewarded with this:
They were gone.... completely gone.
I actually had a large clump of Cerium Oxide that landed between one of the rocks, and the side panel on the left of the tank. It never dissolved, and stayed there in the tank for the entire duration of the tank's lifespan. Nothing died, nothing was poisoned, and I even had some of the best Blyxa roots growing directly through the cerium oxide that never dissolved inside of the tank on that side.
Let me know if you have any questions!
My 140gallon, 150x60x60 rimless tank was all set up. Plumbing installed, stand built, 400+lb aquarium moved onto the stand...
More than 600 POUNDS of hardscape was added (Manten Stone from Aqua Rocks Colorado). The largest rock required two people to lift and place, as it was over 120lbs alone. I then scaped the tank very carefully, glued everything together with superglue and paper towel. I filled the tank to start the Dark Start cycle.
Then I noticed some superglue dried on the front panel. No problem, let me just grab my sponge:
It turns out, many sponges have aluminum oxide coatings on the scrubby side.
Which is harder than low-iron "starfire" glass that most rimless aquariums are made out of. Which means it will permanently scratch it.
After a quick scrub, my brand new dream aquarium had a 2" patch of VERY noticeable scratches:
Oh no.
OH NO. This tank was expensive, the rocks were expensive, it took 4 strong dudes to lift it into place... and I just permanently and majorly scratched it BEFORE IT WAS EVEN PLANTED.
I started researching everything online, and what I saw was very disheartening. 6/10 people say there is no fix, and to either live with it or get a new tank. 2/10 people say that if the scratches are fairly shallow (fingernail can't really catch in the scratch) then you might be able to "sand" or "buff" it with Cerium Oxide to get them out. But, everyone insists the tank MUST be on it's side to do this, it will make a mess, you can't have hardscape inside, etc.
Cerium Oxide doesn't appear to be very toxic, certainly not in weak, diluted solutions. I decided to drain the tank:
Cover the ENTIRE hardscape in as many towels and old t-shirts (the cerium oxide did wash out) as my girl would allow, and even form a watertight packing tape barrier on the front panel where the oxide solution would run down towards the substrate (worked AMAZINGLY well):
I used this Cerium Oxide with this Glass Polishing Wheel on my drill, set to Gear 2 (fastest).
I made a separate solution of RO water and cerium oxide in a squirt bottle to keep the pad hydrated/cool/filled with cerium oxide. Then, I got to work:
After 1.5 hours of nonstop pressure and buffing, I started to see a difference. My arms were killing me.
After 4 hours, the patch of scratches looked like this:
The tape/towel trick to keep the solution from reaching my substrate/bottom worked perfectly (note how there is no solution running below the taped towel):
Finally, after over 8 hours of constant pressure, overheating the drill and the glass (I let it cool frequently), spraying Cerium Oxide around the tank and my room, I was rewarded with this:
They were gone.... completely gone.
I actually had a large clump of Cerium Oxide that landed between one of the rocks, and the side panel on the left of the tank. It never dissolved, and stayed there in the tank for the entire duration of the tank's lifespan. Nothing died, nothing was poisoned, and I even had some of the best Blyxa roots growing directly through the cerium oxide that never dissolved inside of the tank on that side.
My thoughts:
- It works, but I wouldn't dare try this on anything with scratches too deep. Anything more than what your fingernail can catch is likely going to need you to remove a LOT of glass, with what is essentially a 4000-grid sanding solution. It's EXTREMELY tiring work, extremely messy, and not even guaranteed. You could be at it for an hour and not see any improvement.
- Cerium Oxide doesn't seem to be too toxic. I was able to do this in a tank that I didn't remove my hardscape and substrate from and didn't have any issues. Plant roots even grew through the remaining droplets I couldn't remove/reach. There was definitely some C.O. solution left when I filled and cycled the tank. It never dissolved, I had to siphon it out or just leave it.
- Use LOTS of towels to cover/catch as much as you can.
- When viewed from the side, there is a near-imperceptible "wave" in the glass where I buffed it. Of course there is -- I was sanding/buffing the glass/surrounding glass down until the scratches disappeared. This "wave" cannot even be detected from the front and is very subtle. Even my single-blade algae scraper can scrape algae in the "wave" no problem, because it's not that deep.
- Keep the sponge and solution very wet with cool water to help temperature control on the glass. My glass is so thick (17mm) that I didn't worry much, but maybe thinner glass might shatter if it gets too hot, then suddenly too cool?
- BEWARE SCRUBBY SPONGES. I don't know if regular green glass is literally stronger on the Mohs scale, but this S**t was no joke -- 3 seconds of scrubbing my glass with a BRAND NEW scrubby sponge created these scratches. I didn't believe it,. so I went into the garage and tested on an old rimless low-iron tank, and it did the same. DO NOT USE SCRUB SPONGES ON YOUR LOW-IRON TANKS.
- Most of all, I AM SO GLAD I DID THIS. This tank is basically a 2,000+lb installation in our front living room. It's plumbed with water-in water-out parts, lights installed/hanging from the ceiling, and a floor that was engineered and supplemented to handle the weight of this aquarium. If I had left this large patch of scratches on the glass, it would have killed it for me. My glass needs to be absolutely scratch free for a gallery-like tank (this is the first thing people see when they enter our house). I paid $1,700 for the glass tank alone... what a shame to have scratches like that!
Let me know if you have any questions!
