3xl 900

adam.1 · Wednesday at 9:28 PM

I acquired a red sea 3xl 900 for free. The rains Seam is failing at the top right but is not leaking yet. I know everyone is either going to say buy a new tank or completely tear down and rebuild. I’m thinking if I cut out the front panel and built the front panel the only area where old silicone metal new would be the two front bottom corners since it’s front floating glass. Then I add a bottom euro brace to those 2 areas. I have essentially now eliminated the new to old silicone and strengthened the front bottom seams. I would also eurobrace the top. Thoughts?

UncommonSense · Wednesday at 10:19 PM

adam.1 said:
Thoughts?

Several!

You’ll still have the rear vertical seams to contend with, and the rear-bottom seam… these tanks do like to peel from the top-down, if they don’t fail from the bottom center!

The overflow box should be 1/4” (technically 6mm) black smoked glass, you would be best-off also cutting this out and rebuilding it with quality silicone,,considering that a failed overflow seam means the tank can theoretically drain down to the point of failure into the sump, then onto the floor during a power outage!

The tank’s bottom silicone seam inside the overflow box poses another challenge, given that the bulkhead holes are WAY too close to the edge of the bottom pane for both comfort, and for ATSM C1048 standard… you can’t really get glass in there to brace the seam with the bulkheads in the way! (I worked around this on my project tank by doubling up the overflow box’s bottom with a second glass layer, though this comes with many of its own complications)

Regarding bulkheads, Red Sea uses a proprietary plastic “pass through” collar siliconed down to the tank's bottom pane for each bulkhead hole, with the plumbing threading through that… the last G2 reefer I disassembled had four of these plastic pass throughs peel off the glass by-hand… I recommend deleting them and using proper bulkheads in the factory holes!

All this is to say that there’s not a single drop of factory silicone on this tank that you should really trust, and your plan only fixes the damage you can currently see (eurobracing aside)!

Here’s some further “light” reading on the subject from my current Reefer 450 project tank:

https://www.reef2reef.com/threads/the-frankenreefer-450.1147222/

adam.1 · 2026-10-15T06:25:53-0400

@UncommonSense I have been reading these types of build threads obsessively lately. Obviously your idea is the best to prevent future failures. And I knew that was what everyone would essentially say. “Why risk it”. I read in your post you obtained glass from another tank. The 3xl uses 19mm glass so about 3/4”. I do not have another tank with that thick of glass nor do I think I’d be capable of finding one. I have a glass shop I use for work but I’d think they’d be pretty pricey. I also have no clue how to cut glass. Especially that thick. Are you aware of a source online who will make strips to my specifications? Sounds like it’s time to get more suction cups and clamps.

UncommonSense · 2026-10-15T13:30:51-0400

adam.1 said:
Are you aware of a source online who will make strips to my specifications?

Unfortunately, no options exist that I’m aware of, at least at anything resembling a sane price… I searched quite extensively for a manufacturer of triangular or square glass rods around a year and a half ago, only to discover that pretty much everything on the market is extruded (meaning corner aren’t square, and faces aren’t flat), and is made of borosilicate glass (which has a different thermal expansion rate than standard soda-lime glass)…

I ended up speaking to some very talented folks in the scientific glassblowing industry whom assured me that the right blade on a good wet saw would actually cut glass quite well, which led me down the rabbit hole of glass coldworking to manufacture my own square/plane glass rods, strips, and much more! (The thin vertical seam reinforcement rods in particular are a part which cannot be reliably made via conventional scoring/snapping methods, purely because they are equal in width to the glass thickness!)

This said, I’d be happy to offer advice on how to cut your own 19mm glass… or I could potentially source/cut some for you, though I’d imagine you can get it done at a lower cost if you go through the shop you used to work at and cut your own from annealed 19mm sheet!

adam.1 · 2026-10-15T19:31:24-0400

UncommonSense said:
Unfortunately, no options exist that I’m aware of, at least at anything resembling a sane price… I searched quite extensively for a manufacturer of triangular or square glass rods around a year and a half ago, only to discover that pretty much everything on the market is extruded (meaning corner aren’t square, and faces aren’t flat), and is made of borosilicate glass (which has a different thermal expansion rate than standard soda-lime glass)…

I ended up speaking to some very talented folks in the scientific glassblowing industry whom assured me that the right blade on a good wet saw would actually cut glass quite well, which led me down the rabbit hole of glass coldworking to manufacture my own square/plane glass rods, strips, and much more! (The thin vertical seam reinforcement rods in particular are a part which cannot be reliably made via conventional scoring/snapping methods, purely because they are equal in width to the glass thickness!)

This said, I’d be happy to offer advice on how to cut your own 19mm glass… or I could potentially source/cut some for you, though I’d imagine you can get it done at a lower cost if you go through the shop you used to work at and cut your own from annealed 19mm sheet!

@UncommonSense Ok I will look into my local glass shop. I understand the exercise of an abundance of caution dealing with this much water. I took this on planning to rebuild the whole tank. Do you not have faith in the bulkheads redsea uses? I get they are siliconed in and you have no faith in the silicone Red Sea uses but would it be a bad idea when rebuilding the whole tank to use the factory bulkheads with quality silicone? Or is the issue not being able to get the old silicone off the old bulkheads? Reason I ask is I really like how clean the plumbing is and when I start adapting to non metric it’ll never be as clean. What is your opinion on the stand. Do you think the stand has anything to do with the failures? The stand I have has the metal angle iron over the doors to support the front floating glass.

UncommonSense · 2026-10-15T21:36:40-0400

adam.1 said:
Do you not have faith in the bulkheads redsea uses? I get they are siliconed in and you have no faith in the silicone Red Sea uses but would it be a bad idea when rebuilding the whole tank to use the factory bulkheads with quality silicone? Or is the issue not being able to get the old silicone off the old bulkheads?

They aren’t really bulkheads so much as plastic inserts, held in place/sealed by the factory silicone…

I lack faith because these literally popped straight out with hand pressure only, with very little silicone left sticking to the glass… I could definitely see them working if you reinstalled them with quality silicone, though getting the factory silicone off the plastic might require a wire wheel and some inevitable plastic abrasion!

adam.1 said:
What is your opinion on the stand. Do you think the stand has anything to do with the failures?

Assuming the plastic lamination over the particle board is intact, and no water has crept in/swelled the particle board via the fastener holes, it should still be safe to use! I believe this would be a G2 tank, so the stand has leveling feet, correct?

adam.1 · 2026-10-15T21:59:34-0400

UncommonSense said:
They aren’t really bulkheads so much as plastic inserts, held in place/sealed by the factory silicone…

I lack faith because these literally popped straight out with hand pressure only, with very little silicone left sticking to the glass… I could definitely see them working if you reinstalled them with quality silicone, though getting the factory silicone off the plastic might require a wire wheel and some inevitable plastic abrasion!

Assuming the plastic lamination over the particle board is intact, and no water has crept in/swelled the particle board via the fastener holes, it should still be safe to use! I believe this would be a G2 tank, so the stand has leveling feet, correct?

You are correct, g2. My quarrel with the bulkhead issue is I have standard bulkheads fail being brand new and I fixed it with silicone. Is a rubber gasket better than silicone?both are held in by a retaining nut. I did notice though this tanks retaining nuts were barely hand tight. I don’t think so if proper materials Are used. I think I will use the oem bulkheads if possible. Tear down will determine I guess. The stand is in great shape. I did tear one leveling foot off in transport which seems like a win considering the weight and logistics of this move. It was on the 25th floor of a condo. The tank had to be flipped on end to fit in the elevator.

UncommonSense · 2026-10-15T22:28:53-0400

adam.1 said:
It was on the 25th floor of a condo.

This would have been ugly if a seal completely failed!

adam.1 said:
My quarrel with the bulkhead issue is I have standard bulkheads fail being brand new and I fixed it with silicone. Is a rubber gasket better than silicone?both are held in by a retaining nut

I understand your sentiments… I too have had issues getting some brands of bulkhead to form a solid seal! Though, since I’ve switched to bulkheads from one of a few known brands (Hayward, Lifegard, etc…), I actually can’t recall my last leaker!

I think the primary advantage with a rubber gasket vs. silicone is the ability to service the seal for the lifetime of the tank; proactively replacing cheap rubber gaskets when they start to age out and get hard/cracked!

This said, it’s entirely possible that the factory siliconed-down “bulkheads” are more than sufficient, assuming you use a soft wire wheel to remove old factory silicone and scuff up the plastic surface before applying a quality silicone to reinstall them! (Just be sure to double check the sizes of the o-rings on the factory plumbing which unthreads from these “bulkheads”, as they are effectively your bulkhead gaskets in the factory design, and may need to be replaced at some point down the road!)

adam.1 said:
I did tear one leveling foot off in transport

This would be best reinstalled using some form of two-part epoxy, which will also serve to seal the surrounding exposed particle board from water ingress, and subsequent swelling!

adam.1 · 2026-10-16T11:04:31-0400

UncommonSense said:
This would have been ugly if a seal completely failed!

I understand your sentiments… I too have had issues getting some brands of bulkhead to form a solid seal! Though, since I’ve switched to bulkheads from one of a few known brands (Hayward, Lifegard, etc…), I actually can’t recall my last leaker!

I think the primary advantage with a rubber gasket vs. silicone is the ability to service the seal for the lifetime of the tank; proactively replacing cheap rubber gaskets when they start to age out and get hard/cracked!

This said, it’s entirely possible that the factory siliconed-down “bulkheads” are more than sufficient, assuming you use a soft wire wheel to remove old factory silicone and scuff up the plastic surface before applying a quality silicone to reinstall them! (Just be sure to double check the sizes of the o-rings on the factory plumbing which unthreads from these “bulkheads”, as they are effectively your bulkhead gaskets in the factory design, and may need to be replaced at some point down the road!)

This would be best reinstalled using some form of two-part epoxy, which will also serve to seal the surrounding exposed particle board from water ingress, and subsequent swelling!

Any recommendations on silicone? I have asi but would there be a better option? After lots of research I think k the injection method is my best option given the size and weight of these panels.