Drilled overflow to canister intake conversion

[Turtlemaxxx]

Has anyone ever removed the factory overflow black box and hooked a canister up to the holes in the bottom of the tank before? I seem to remember seeing it done but can't find any now that i'm thinking about doing it.

[msawdey]

I have definitely seen this done on this forum, but I cant seem to find any of the posts

[jmhart]

Originally Posted by Turtlemaxxx

Has anyone ever removed the factory overflow black box and hooked a canister up to the holes in the bottom of the tank before? I seem to remember seeing it done but can't find any now that i'm thinking about doing it.

Originally Posted by msawdey

I have definitely seen this done on this forum, but I cant seem to find any of the posts

I did it on my 120g. Link in my sigature. Love it. Happy to answer any questions you might have.

[msawdey]

thats exactly where i have seen it! Thanks Jeff

[jart]

I think Craigthor has as well.

[talontsiawd]

Seen it done many times. I am not sure that I am correct but some people find it to be risky. Reason being is if the power goes out or you trip a GFIC, the siphon is still going and pulls excess water into your filter and it's not pushing anything out. Not sure its really an issue but I know some people say it's not the best idea.

[Turtlemaxxx]

I would be hooking up an fx5 to it and was curious about the inlet being at the bottom of the tank. Worried about a failure emptying my whole tank onto the floor. Any way to prevent that?

[jart]

There are some references to bottom drilling in this thread. Check out Wasserpest's post.

As far as preventing your tank draining if the bulkheads leak or the canister's seal was to fail... not much that I can think of. Some people plumb in check valves, but these can certainly fail, although the clear ones could at least allow you to check the inner workings every so often.

[jmhart]

Originally Posted by talontsiawd

Seen it done many times. I am not sure that I am correct but some people find it to be risky. Reason being is if the power goes out or you trip a GFIC, the siphon is still going and pulls excess water into your filter and it's not pushing anything out. Not sure its really an issue but I know some people say it's not the best idea.

This is not an issue at all. That's not how physics works. The filter loop holds as much water as it will ever hold. In the event of a power outrage it just stops flowing just like any other filter setup.

[mott]

It's still a closed system, no worries if all bulkheads and canister are sealed well.
If the intake is gonna be at the bottom of the tank just make sure you keep it clean and free from clogging, you don't want to starve the pump.

[jmhart]

Originally Posted by mott

It's still a closed system, no worries if all bulkheads and canister are sealed well.
If the intake is gonna be at the bottom of the tank just make sure you keep it clean and free from clogging, you don't want to starve the pump.

This is true of any filtration device, not just bottom drains.

[Diana]

A way to help reduce the water on the floor failure from plumbing failure. Does not help if the bulkhead fails:

Intake can be near the bottom.
Pipe goes UP while still in the tank. Makes a U and goes down and out through the bulkhead.
Drill a hole in the pipe near the top that is under water most of the time, but will be exposed if 'too much' water drains out. 'too much' might be 1" or 2" below your desired water level. Not too high, you do not want evaporation to expose this hole. Not too low. When water is draining out because of some failure in the pipe you will have that much on the floor. You can set up a tray under the tank to catch this, but more water = bigger tray.
You will need to do more research to find the optimum size of this hole.
On my tank, I bought a kit that has the holes already there. 2 holes, opposite sides of the pipe, about 1/4" each.

This will work if there is a power failure. When the pump stops pushing water into the tank the level stops rising. Then whatever is in the pipe COULD start a siphon, draining out through the failed pipe, or cracked canister. When the water level hits that hole near the top air enters and breaks the siphon.
This will work if the power is still on. The pump keeps running, but water is leaving the system through the break. When there is less water in the system the level gets lower in the tank. When the siphon breaks no more water enters the filter. This could burn out the pump.

Most of the failures I have had have been slow leaks, not catastrophic. By sitting the canister in a shallow container (dish pan or similar) you will see a slow accumulation of water and will be able to do something about it. A 5 gallon bucket or other deep container is OK, but it is harder to get the filter in and out to clean it when the bucket and filter are under the tank, in a tight space. I have used both, and prefer the shallow container. It is not that much water when the problem starts slowly.

I have not had plumbing failure due to faulty pipe, fittings or assembly (I have done PVC for more years than I want to think about and I just do not 'do leaks'.)
Failures have always been the canister. Usually the O-rings, which is a maintenance item. They start to leak, buy new ones.

[blink]

Or even simpler than Diana's suggestion is a simple standpipe for the intake that sits an inch or two below the surface with a strainer on it.

[jmhart]

Originally Posted by blink

Or even simpler than Diana's suggestion is a simple standpipe for the intake that sits an inch or two below the surface with a strainer on it.

This is the exact setup of my tank. Intakes are positioned about 2" above the substrate so in the event of a failure the yank doesn't completely empty and my fish all survive.

In my tank I've never had a leak due to having a bottom drain. The only issue I ever had was a failure in my drain valve causing it to drain excessively. The above setup is what kept my fish alive.