Noise reduction hob overflow

[Lowstorm]

Howdy. I am in need of ideas on how to reduce my noise. And its not the normal flushing/gurgle noise. Nope, I have to be 'special'. I'm getting noise from the water crashing down into my overflow box before the drains! I lowered the box a little and that helped.. but didn't eliminate it.

I had no noise but for the return pump hum, then I went ahead and upgraded pumps, doubling my flow. I have an eshopps pf-1200 overflow. I was running a whimpy ehiem 3000+, which was pretty gunked up by this time (Have had the tank going since Feb 1st) and only had one of the overflow tubes going.

I got myself a jebao 6000, over doubling my return pump flow. (I'm keeping the eheim on hand, just in case-ya never know, right?) So now I'm using both overflow tubes, yay! But my wavemakers are making the water level go up, and down, and all around. And now it sounds like I have a raging river crashing over the rocks, because of the water going over and down into the black part of the overflow box.

My idea is to just get some really big floss or something like that, so that the water is a bit slower going into the box. I could also lower the box a little more (Which I'm going to try right after I get done typing this).

FWIW I've never ran this much flow through a sump, my biggest tank prior to this was a 75 gallon, and I had a small ehiem on there too. Probably the same flow as the one I have now.

 

[Lowstorm]

Neeevermind, I fixed it. What I did was lower one side a lot, and I have some ceramic tiles from my ipsf order (coralline algae seeding plates). I put one of those in the lower side, angled so the water has to flow into the box, then fill to overflow that too. Silence is great!

Oh, and I angled my return line so its breaking up the crashing from the wavemaker, so that helped the most, then the lowering of one side.

 

[mcarroll]

Cool it's solved!

Check your flow rate - usually that situation is caused by flowing more water than your drain can silently handle.

You may have gone overboard with the pump upgrade. You really want that extra flowrate in the tank, from a power head....the sump flow is just to get dirty water to the sump and clean water back to the tank. Trying to create flow in the display tank with a return pump is borderline futile - many watts for very little flow.

The rule of thumb I like for sump flow is 2x to 4x your display tank's volume. If the filter treats your whole tank volume two to four times in an hour, you would be set in almost all scenarios.

This flow rate is generally silent and management-free in a gravity drain like yours.

And I'm talking about actual flow rate not just the pump or drain's rating. Stick a bucket under the return or drain (whatever is easier) and time how long it takes to fill to a certain volume. Convert the time to hours and the volume to gallons and voila you have your tank's actual return flow rate in GPH!

For a 125, you'd figure it like this:

125 gallons
x2
=250 gallons per hour

x4
= 500 gallons per hour​

That probably doesn't seem like a lot, but trust me (or ask around!) 2x-4x really is plenty for skimmers, heat, etc, you have in the sump. :)

You might decide to "over-build" allowing for the system to age and plumbing to fill in with bio-films, etc over time and set your flow at x5, assuming it will decline over time into the 2x to 4x range....beyond that is really overkill and more or less a waste.

x5
=625 gallons per hour​

 

[Lowstorm]

No, I actually am still running under what my overflow can handle. It's sucking more than the tank is refilling. Now that it's tweaked it's working good.

 

[mcarroll]

You're describing a drain that is being over-run by too much flow. ;)

Over-running the drain creates a temporary siphon in the drain plumbing which sucks all the water out at high speed...sooner or later the siphon breaks (no more water) and the drain box fills up to repeat the next round of sucking/flushing.

A typical gravity drain is not really meant to be high-flow....it's meant to be quiet and reliable. Gravity drains for aquariums are sized (generally) to be silent with the "normal" amount of flow....two to four times your display size, in actual gallons per hour.

You can certainly design a gravity drain for more flow that will still be silent, but larger plumbing is needed. The best alternative for high flow is to do a "Bean Animal" or "Herbie" type of drain that incorporates multiple drains and/or a permanent siphon to the typical setup. I don't like the stockman/maggie type "silencers".

And again, I'm glad you got it working....it's just something to think about now. :D:D:D

 

[Lowstorm]

It's a totally different animal. A hob overflow doesn't work the same way at all from drilled, herbie, etc. If I was pushing too much flow the box hanging off the side would start flooding... and I'd have a mess. A hob has an intake box, 2 tubes running over the top of the tank into a hanging overflow box. People have made herbies, etc back there for noise reduction. I don't mind that noise.

So, yes.. If I had a drilled tank I'd totally be with you :) but my tank has no holes in it.

 

[Lowstorm]

I figured I'd add on to how it works. The siphon slows to a stop when the water level in the in-tank box gets low enough, making it possible for me to turn off all my power and it just starts up again. Really neat system. Over I was pushing too much water my tank would flood. What my problem was that my large amount of flow was dropping too far into the prefilter box. I could probably handle another 200gph and not have trouble.

 

[Lowstorm]

And yes, I'm putting a lot of water through my system. I'm loving it! Lol.

 

[mcarroll]

;):D

Not totally different. For example, everything I typed applies.

;)

 

[smiley28]

You're describing a drain that is being over-run by too much flow. ;)

Over-running the drain creates a temporary siphon in the drain plumbing which sucks all the water out at high speed...sooner or later the siphon breaks (no more water) and the drain box fills up to repeat the next round of sucking/flushing.

A typical gravity drain is not really meant to be high-flow....it's meant to be quiet and reliable. Gravity drains for aquariums are sized (generally) to be silent with the "normal" amount of flow....two to four times your display size, in actual gallons per hour.

You can certainly design a gravity drain for more flow that will still be silent, but larger plumbing is needed. The best alternative for high flow is to do a "Bean Animal" or "Herbie" type of drain that incorporates multiple drains and/or a permanent siphon to the typical setup. I don't like the stockman/maggie type "silencers".

And again, I'm glad you got it working....it's just something to think about now. :D:D:D

The tanks I just bought has a bean animal overflow which I'm very impressed with. I can dial in a gph with my vectra and adjust the overflow just under the emergency drain for nearly complete silence. You could also use any fixed rate pump.