Resealing a 220g tank....difficulty level?

Canuck007 · Oct 18, 2018

So I'm buying a 220g 72x24x30h tank with center overflow, top and bottom trim, from a local reefer for a good price. Few scratches on sides but nothing on the front. Not sure of tank age but probably 5 yrs plus.
He suggested I probably should reseal the bottom of the tank. He said its not absolutely necessary but best to do it now instead of 2-3 yrs from now.
Is resealing a difficult job? I see it on YouTube and doesnt seem that hard...always looks that way until you have to do it. TIA

dugthefish · Oct 18, 2018

Following g

Labridaedicted · Oct 19, 2018

I did an interior reseal on my 180 that i picked up used. It's not a super difficult job, but it is very time consuming. You have to remove ALL the interior silicone. Silicone does not adhere to cured silicone, so it is imperative that all of it is removed including the residue looking film that tends to stick behind. You'll go through a tooooon of razor blades in this process, so buy a 100 pack at lowes/hd. The overflows for me were the most difficult part as they must be removed to get a complete interior reseal and those puppies are on there TIGHT! Lots of silicone and unlike the edge seams, you have to get between the plastic and glass. I found a guitar string worked best for me at this. thread it through then pull on both ends and it will cut through like butter (hard frozen butter, but you'll get through it)

Afterwards, clean all the corners with alcohol or another solvent. This will ensure there's no oils that will prevent adhesion of the silicone. You'll likely find more silicone remnants in this process.

Now, you can begin the reseal. Pick up a tube of high quality silicone (I recommend Momentiv RTV 108 for strength. I know this silicone is not holding much is any weight, but always better to go stronger than necessary than not....) and load your caulking gun. I went through about 3 tubes on my 180 (i did big ol fat seams on the bottom) tape out the edges you want with painters tape for a clean line later. I cut an old store discount card of some kind to make the shape of the seam. You'll need to work quickly to make sure you get the seams done before the silicone cures but if done right, you'll be able to have one solid piece of silicone once cured. This is easiest if you have 2 people. one person shoots the silicone and the second person shapes it with the trimmed card. (Wear rubber gloves as you will get silicone everywhere and it makes a mess)

Lastly, reinstall the overflow once the other silicone is cured. Let this all cure for a week and then feel free to leak test.

If done right, you'll have a nice new set of seams that should last a long time! It will be nerve wracking on a large tank (or it was for me.....) but as long as the structural seams are still nice and strong, they'll be what holds the tank together. This just protects those.

This took me about 4 hours a day for 3 days to do this. (plus a few painful hand cramps while scraping the silicone.....) IT's a labor intensive job, but not difficult, just tedious.

Rcpilot · Oct 19, 2018

Labridaedicted said:
I did an interior reseal on my 180 that i picked up used. It's not a super difficult job, but it is very time consuming. You have to remove ALL the interior silicone. Silicone does not adhere to cured silicone, so it is imperative that all of it is removed including the residue looking film that tends to stick behind. You'll go through a tooooon of razor blades in this process, so buy a 100 pack at lowes/hd. The overflows for me were the most difficult part as they must be removed to get a complete interior reseal and those puppies are on there TIGHT! Lots of silicone and unlike the edge seams, you have to get between the plastic and glass. I found a guitar string worked best for me at this. thread it through then pull on both ends and it will cut through like butter (hard frozen butter, but you'll get through it)

Afterwards, clean all the corners with alcohol or another solvent. This will ensure there's no oils that will prevent adhesion of the silicone. You'll likely find more silicone remnants in this process.

Now, you can begin the reseal. Pick up a tube of high quality silicone (I recommend Momentiv RTV 108 for strength. I know this silicone is not holding much is any weight, but always better to go stronger than necessary than not....) and load your caulking gun. I went through about 3 tubes on my 180 (i did big ol fat seams on the bottom) tape out the edges you want with painters tape for a clean line later. I cut an old store discount card of some kind to make the shape of the seam. You'll need to work quickly to make sure you get the seams done before the silicone cures but if done right, you'll be able to have one solid piece of silicone once cured. This is easiest if you have 2 people. one person shoots the silicone and the second person shapes it with the trimmed card. (Wear rubber gloves as you will get silicone everywhere and it makes a mess)

Lastly, reinstall the overflow once the other silicone is cured. Let this all cure for a week and then feel free to leak test.

If done right, you'll have a nice new set of seams that should last a long time! It will be nerve wracking on a large tank (or it was for me.....) but as long as the structural seams are still nice and strong, they'll be what holds the tank together. This just protects those.

This took me about 4 hours a day for 3 days to do this. (plus a few painful hand cramps while scraping the silicone.....) IT's a labor intensive job, but not difficult, just tedious.

Nice write up

cracker · Oct 19, 2018

How well ya know this guy? Will he let ya fill test before Any cash is involved? how long has it been sitting empty ?
@Labridaedicted About nailed it. be real careful not to cut the silicone between where the glass meets. Good luck, it will come out fine !

Ron Reefman · Oct 19, 2018

IMHO just doing the inside bead of silicone isn't really doing much. I feel that the seal between the glass panels is 98% of the tank seal and the bead laid down in the corners (the part discussed above) is hardly even worth doing... is just poor insurance and it's so easy to damage when cleaning the glass after it's full. I've built 6 tanks from scratch, so I have some experience. However, being completely fair here, the biggest have been 65g, so not nearly the 220g you are looking at. But my last 3 tanks I haven't even bothered with the inside bead as I consider it almost (yes, I said ALMOST) useless. Look at some of the new high end tanks being sold these days, they don't bother with the inside bead either!

OK, all that said, I think you should consider 3 options, one is super easy and one is incredibly difficult and one is barely worth doing:

1) Just clean up inside the tank as best you can and don't worry about redoing the inside bead. However, give the tank a serious water test outside your house!

2) Take the tank completely apart and redo all the seams. This is both very time consuming and difficult to do correctly... and will require at least 1 or 2 other people when you start to put it back together. Big glass panels are heavy and setting them onto the silicone needs to be done perfectly the very first time. If you screw it up the new silicone will have to be completely removed before you try again.

3) Do what you are considering, redo the bead along the inside of the seams. It's a fair amount of work. Be VERY careful that you don't get your blade between the panes of glass and screw up the seal between the panels. As Labridaedicted stated above, get every last tiny, thin film of old silicone off the glass, it's critical if it's going to be worth doing. And do NOT use any chemicals to try and remove the old film. It can get at and into the silicone between the panels.

Whatever way you go, good luck.

Canuck007 · Oct 19, 2018

Thank you all for your advice. Excellent info. It seems rather time consuming and I just didn't know if I have the time right now. I'll have think about this...

Rcpilot · Oct 19, 2018

Buy a new one?
I bought a new Marineland 180g dual overflow recently. $1,500
Worth the cost considering they offer a full lifetime warranty. 180g of water would do a lot of damage to a house. Even with tile flooring, you'd still have drywall and baseboard damage. Wife wouldn't be happy for a long time.

Canuck007 · Oct 19, 2018

Yeah I'm considering new...i can get a aqueon 210 here from lfs for $1300 delivered and placed on my stand...it's 4 times the cost of the used 220 but brand new....unfortunately warranty is no good if you don't use their stand...or just wait for a good deal to come out on Craigslist...i looked at custom and for 200-250 gallon tank its well into the 2000s. Did you buy your marineland from lfs or online?

cracker · Oct 19, 2018

I recently bought an Aqeon for 9 hundred something it was delivered to my lfs.

Canuck007 · Oct 19, 2018

I checked a number of places here and $1300 lowest I found with tax and delivery...i dont have people or a truck to help me move it...do you like the tank?