Leaking Bulkhead

[cpeguero]

I have a slow leak on one of my closed loop bulkheads. I hadn’t noticed it until a couple of months ago, and it seems to have gotten a little worse. I tried sealing around the interior of the bulkhead by putting a collar with sealant around it inside the tank. Unfortunately, either this didn’t seal well or that wasn’t the source of the leak. Now I’m afraid I cracked the bulkhead at some point while tightening it to initially stop the leak. The tank is 260 gallons, and the bulkhead was s near the bottom. Pics below. 
 

I see four potential courses of action:

 

1 - make more collars for the outside of the tank and seal the bulkhead on the outside. This seems like a bandaid and some that wouldn’t last long term. 
 

2 - make a coffee dam around the bulkhead that would allow me to replace it without draining the tank. This is the lowest impact to the tank, but there’s risk of knocking the coffee dam out and causing a catastrophic flood while the bulkhead is out. Also, I have no idea how hard it will be to remove the sealant I already put in. 
 

3 - drain the tank far enough to replace the bulkhead. This is the most secure, but also the biggest pain in the butt. I’d probably have to remove a lot of the fish, since the water level would be too low for the tangs to swim around. I’d save the water, so refilling wouldn’t be a big deal. 
 

4 - try number 3, but be ready to implement number 4 if anything goes wrong. 
 

anyone have any thoughts on any of this?

 

 

[epleeds]

Can u just tighten it slightly and see if that fixed the issue. It could have just come loose enough for it to start to drip 

[cpeguero]

I could, but I’ve already tightened it multiple times in the last month while trying to address this. I might try again to avoid draining off possible….

[zygote2k]

Looks like there’s a ton of cyano in there.

im willing to bet there’s lots more undesirable detritus and dirt in there too.

Good excuse to do a drain, clean, fix bulkhead, and refill.

And for what it’s worth, it’s a Coffer Dam.

[cpeguero]

Lol. Auto correct got me🙃 though a coffee dam might have been to blame 😉

 

I’m leaning toward a combination of 2 and 3. I realized two additional issues with a coffer dam:

 

1 - I can’t build one all the way to the bottom of the tank because there are reinforcing braces on the bottom

 

2- if I build one that goes just underneath the bulkhead, there will be about 35 pounds of buoyant force pushing it up.  I’d need to find a way to either put that much weight in the bottom or have it but up against my euro brace, and I don’t like the idea of putting that much upward force on my euro brace, as it wasn’t designed for that. 
 

so now I’m thinking drain down to around the level of the bulkhead, build a small coffer dam that will fit around it. This should keep the water level deep enough for my fish to still be ok for the time I’m working on the bulkhead, and make access easier. 
 

I may still just go ahead and drain down. Going to be stressful for the fish no matter what, but it may be more stressful being in so little water. Goi g to be a pain to get all of them, especially the ones that are really good at hiding - mandarins, gobies, blenny, firefish…. But then again, if I don’t drain completely, they may be ok in their bolt holes, while the bigger fish swim around in a holding tank….

 

going to be a few weeks before I do this, as a shoulder injury is going to prevent me from doing anything until it heals. So still open to input on best course of action.