What is the advantage of wet dry vs conventional sump

[anewbie]

I'm not sure i'm allowed to link swisstropical but if you go to their site they have two pictures of a conventional sump and wet dry sump. The primary difference is they have a sponge sitting above the water line and spay the water down into (wet/dry) vs having the water enter the sump and flow through a series of submerged sponges. There are many other implementations but the basic difference is that wet/dry tend to have some media out of water that intake water trickle over before entering the sump. 

For freshwater only can someone explain the advantage of having the 'dry' media sitting outside the sump. I presume that having some of the media exposed provides some ?perceived? benefit over having all the media submerged i just can't find a good explanation of that benefit and if it is relevant to freshwater or only relevant to salt water.

[Keeg]

I am NOT an expert on sumps, canister filters are my go to for filters and sumps for looks. Sumps are usually the best option for saltwater tanks because of the extra care into balancing the tank. But in freshwater, sumps are in my opinion, over complicated when it doesn't need to be. Usually wet/dry sumps are that way to aerate the water if you dont want big splashes at the surface. So my best guess, to have slow surface movement like a pond or bog set up. 

So not really an advantage unless you're going for a specific style. 

Edited August 27, 2021 by Keeg

[anewbie]

On 8/27/2021 at 4:37 PM, Keeg said:

I am NOT an expert on sumps, canister filters are my go to for filters and sumps for looks. Sumps are usually the best option for saltwater tanks because of the extra care into balancing the tank. But in freshwater, sumps are in my opinion, over complicated when it doesn't need to be. Usually wet/dry sumps are that way to aerate the water if you dont want big splashes at the surface. So my best guess, to have slow surface movement like a pond or bog set up. 

Sumps don't splash. The wet dry refers to the water flowing into the sump and media location; surface movement et all is how you return the water to the tank and is not relevant to if the sump is wet dry or conventional.

[eatyourpeas]

I have a sump in my SW tank, and use the W/D method for the first layer as an easy way to separate solids before they get mixed in further down the filter. I have canisters in all my FW tanks, but none of them is big enough to justify a sump.

@OnlyGenusCaps is looking at a sump with a refugium for his FW cichlid tank, and I think it is primarily a way to run filtration when you do not have a planted tank. Look him up and follow his builds from the signature.

Some people also run MBBR, but I do not have that need since my filtration is mostly mechanical.

[Keeg]

On 8/27/2021 at 2:40 PM, anewbie said:

Sumps don't splash. The wet dry refers to the water flowing into the sump and media location; surface movement et all is how you return the water to the tank and is not relevant to if the sump is wet dry or conventional.

I have a sump on one of my tanks and I just assumed they all return the water the same. I am not an expert lol, but I still think its to aerate the water more. 

[OnlyGenusCaps]

Are people talking about sumps?!  I love sumps!!!  😁

I'm glad that you, @anewbie recognize that sumps are now just for SW tanks.  I think they get that reputation because the SW folks, especially the reefers, are far more willing to explore new ideas and not worry about the expense as much than the FW folks.  But this is a huge advantage to us with FW tanks because they have figured out what does and what doesn't work.  And sumps work.  They work great!

In terms of the difference between the wet/dry or trickle tower type of sump and a fully submersed media sump, there are a few things to know.  The big advantage to the wet/dry is that you can better use vertical space, much as @eatyourpeas has done with the Puget Sound Biotope.  They probably do aerate better as well.  That's sort of where the advantages end though.

The disadvantages of wet/dry sumps really come from one little detail that very smart people seem to forget when they deal with aquarium filters: water will take the path of least resistance.  This means that in the "dry" or above the water line component of your media, you can get actual dry spots, and often get places with little flow.  Thus, you end up not taking advantage of the bulk of your media that way.  This tends to make them less efficient than when the media is fully submerged.

It is interesting that you found a wet/dry on a foam seller site as that type of media would be even less efficient in that sort of media.  Whereas foam spanning the potential flow of the water makes a very good media when submerged.  I ran wet/dry filters on smaller tanks in the past because I could get more media in there by using the vertical space, but it ended up being less efficient than using the DIY kits on eBay to make one with fully submerged media. 

I hope this helps.  If you had follow up questions, I'd be happy to answer them to the best of my ability. 

[gardenman]

The advantage to a wet/dry filter is the increased oxygen exposure of the media. Koi fanciers often use Bakki showers which are kind of an extreme wet/dry trickle filter. The fluidized filters using K1 or similar material and using air to fluidize it give you the advantages of a wet/dry filter with no dead spots. They're largely the best of both worlds. You can even add a fluidized chamber in a sump, so they're becoming more the norm. The massive volume of air to fluidize the K1 balances out the aeration one gets with a trickle filter with much less risk of dead spots.

[anewbie]

On 8/27/2021 at 5:54 PM, OnlyGenusCaps said:

Are people talking about sumps?!  I love sumps!!!  😁

I'm glad that you, @anewbie recognize that sumps are now just for SW tanks.  I think they get that reputation because the SW folks, especially the reefers, are far more willing to explore new ideas and not worry about the expense as much than the FW folks.  But this is a huge advantage to us with FW tanks because they have figured out what does and what doesn't work.  And sumps work.  They work great!

In terms of the difference between the wet/dry or trickle tower type of sump and a fully submersed media sump, there are a few things to know.  The big advantage to the wet/dry is that you can better use vertical space, much as @eatyourpeas has done with the Puget Sound Biotope.  They probably do aerate better as well.  That's sort of where the advantages end though.

The disadvantages of wet/dry sumps really come from one little detail that very smart people seem to forget when they deal with aquarium filters: water will take the path of least resistance.  This means that in the "dry" or above the water line component of your media, you can get actual dry spots, and often get places with little flow.  Thus, you end up not taking advantage of the bulk of your media that way.  This tends to make them less efficient than when the media is fully submerged.

It is interesting that you found a wet/dry on a foam seller site as that type of media would be even less efficient in that sort of media.  Whereas foam spanning the potential flow of the water makes a very good media when submerged.  I ran wet/dry filters on smaller tanks in the past because I could get more media in there by using the vertical space, but it ended up being less efficient than using the DIY kits on eBay to make one with fully submerged media. 

I hope this helps.  If you had follow up questions, I'd be happy to answer them to the best of my ability. 

The vertical space doesn't interest me and it sounds like there is no real advantage to being directly expose to air. The sponge guy if you look at his picture uses a spray bar to keep it even across the center of the sponge but of course as you leave the middle of the sponge you get less benefit of the media. I think i'll keep it simple and just have a series of slices  of sponges (his other picture). 

Btw there was a paper that measured bacteria per media density and found that other than k1 (only when used in an mbr configuration); sponge 20ppi and 30ppi were by far more efficient than the various bio-balls and ceramic balls folks frequently buy. It also has the benefit of mechanical filtering so having 4 to 6 slices of sponge seems the way to go.

Edited August 28, 2021 by anewbie

[Randall from Texas]

On 8/27/2021 at 7:11 PM, anewbie said:

The vertical space doesn't interest me and it sounds like there is no real advantage to being directly expose to air. The sponge guy if you look at his picture uses a spray bar to keep it even across the center of the sponge but of course as you leave the middle of the sponge you get less benefit of the media. I think i'll keep it simple and just have a series of slices  of sponges (his other picture). 

Btw there was a paper that measured bacteria per media density and found that other than k1 (only when used in an mbr configuration); sponge 20ppi and 30ppi were by far more efficient than the various bio-balls and ceramic balls folks frequently buy. It also has the benefit of mechanical filtering so having 4 to 6 slices of sponge seems the way to go.

I would love to read this, got a link?

[Biotope Biologist]

I love running sumps too! Especially on freshwater. I understand that there is this idea of volume of water, but for the most part I think it seems rather wasteful to have a sump if you have low waste fish. Maybe that also is why it's seen as a saltwater only thing? 

 

But I've ran them on 40 gallon breeders before and effectively doubling the amount of water in your display tank allows the bacteria to really get going and the mechanical filtration side of it to take effect.

 

You want to talk about unnecessarily complicated though, you gotta talk about bioreactor sumps. I wouldn't run those unless you are running extremely sensitive fish or have a huge bioload. 

 

The only thing I'd like to add on wet/dry sumps is the balance of water pressure and water level is a bit more finicky then just running wet. So you really have to be on top of your evaporative loss so your pump doesn't go dry. At least when you have DIY plumbing.

[Vanish]

My fully submerged sump with a beananimal overflow is dead silent. A wet/dry configuration will make some running water noise. I prefer the silence.

[anewbie]

On 8/27/2021 at 8:04 PM, Randall from Texas said:

I would love to read this, got a link?

This isn't the paper i remember but it seems to have similar results:

https://aquariumscience.org/index.php/7-1-3-filter-media-test/