Why did my aquarium overflow?

Exotic_Reefer0 · Jul 6, 2020

So I have a large sump and I've had it setup for months upon months with everything running smoothly. Today I added 5g to the sump, I decided I just wanted to fill it up higher. Next thing i know the aquarium is overflowing but i never touched the flow control or ball valve. Strange....

andrewey · Jul 6, 2020

It means your return pump is outperforming your overflow. Put another way, you actually just learned a valuable lesson- your overflow is inadequate right now. This is either do to design or tuning, but you will want to rectify this situation immediately. This can occur again even if you don't add the extra volume of water to your sump.

KStatefan · Jul 6, 2020

By adding water to the sump you decreased the head on your return pump so you increased flow.

Exotic_Reefer0 · Jul 6, 2020

andrewey said:
It means your return pump is outperforming your overflow. Put another way, you actually just learned a valuable lesson- your overflow is inadequate right now. This is either do to design or tuning, but you will want to rectify this situation immediately. This can occur again even if you don't add the extra volume of water to your sump.

Very well said.. I guess for my next tank I'll make sure its drilled. I'm using an overflow box right now with 1inch bulkheads which by what ur saying is probably too small

Exotic_Reefer0 · Jul 6, 2020

KStatefan said:
By adding water to the sump you decreased the head on your return pump so you increased flow.

Ahh I see, what do you mean by decreased the head on the pump?

JoshH · Jul 6, 2020

Cruzsam00000 said:
Ahh I see, what do you mean by decreased the head on the pump?

Head pressure is resistance to your flow caused by gravity. The higher you pump a fluid up vertically the more resistance is created and the harder your pump has to work. Your head height is calculated from the height of the water level in your sump/pump chamber to the highest point on your return line.

Because you increased the height of the water level in your sump it decreased the distance between the two which lowered the head height and decreased the resistance on your pump. Less resistance, more flow, meaning more water going to the display. If you don't adjust your main drain to balance it out your tank will overflow, as you have discovered.

ScottB · Jul 6, 2020

That was pretty cool observation by @KStatefan.

And a fine explanation of head pressure by @JoshH. I am glad I read his explanation first before posting the verbal gymnastics I was going through to explain it.

Exotic_Reefer0 · Jul 6, 2020

JoshH said:
Head pressure is resistance to your flow caused by gravity. The higher you pump a fluid up vertically the more resistance is created and the harder your pump has to work. Your head height is calculated from the height of the water level in your sump/pump chamber to the highest point on your return line.

Because you increased the height of the water level in your sump it decreased the distance between the two which lowered the head height and decreased the resistance on your pump. Less resistance, more flow, meaning more water going to the display. If you don't adjust your main drain to balance it out your tank will overflow, as you have discovered.

You guys are awesome lol. Literally a perfect explanation. I appreciate the time you guys are taking to teach me something!

JoshH · Jul 6, 2020

ScottB said:
That was pretty cool observation by @KStatefan.

And a fine explanation of head pressure by @JoshH. I am glad I read his explanation first before posting the verbal gymnastics I was going through to explain it.

Oh come on I want to read it now!!