Under gravel filtration using a sand substrate...

[Colin_T]

Materials clog up when used in the gravel and they will stop the water flow completely. It won't work. I have tried similar things before. Undergravel filters need gravel to work, not sand. If you want to raise Gammarids, use sand and an air operated sponge filter.

 

[jaylach]

Materials clog up when used in the gravel and they will stop the water flow completely. It won't work. I have tried similar things before. Undergravel filters need gravel to work, not sand. If you want to raise Gammarids, use sand and an air operated sponge filter.

You may be totally correct but I'm still probably going to try anyway just to satisfy my own curiosity. It will either work or it wont. If it does not I'm not really out anything but the filter plates. I WILL run it for a couple of weeks with the air riser caps above the water level to monitor the water flow for a while. It is sort of amazing how much water a Whisper 20 can move. I run dual Whisper 20s on my 20 gallon, one for each air riser, and they will still move water with the riser caps 3-4 inches above the water level when I'm doing a water change.

I have decided to scrap the idea of making little domes though. That was sort of dumb. I will just use a sheet of very fine nylon mesh I already have. The mesh was gotten for an idea that I decided didn't stand a chance. I was going to put the mesh over the gravel substrate and cover with sand. Dawned on me that the mesh would make it impossible to vacuum the gravel.

 

[Sgooosh]

Sorry but I'm old and don't get all abbreviations. Could you define MTS? Somehow I think I should know but don't.

Yes, I fully understand that sand is much denser than gravel and would restrict water flow but that MAY be self solving as the sand density would mean that no more than half the depth would be needed. With gravel you want 3-4 inches. With sand I'd bet you could get the same results with 1.5-2 inches.

Not a direction I think I want to go but there could even be argument made for reverse under gravel filtration for a sand substrate. There is a guy in a local aquatics group on Face Book that absolutely swears by this for crustacean tanks but but I think he is using gravel.
<edit for self correction>
Reverse UG filtration would not work with sand as it would necessitate not using the mesh domes as they would clog from the bottom and a siphon could not clean. Without the mesh domes sand would then sift to under the filter plates further blocking water flow.

Hey, if I try this with a 5 gallon scud tank I already have nylon mesh to keep the sand from sifting through the plates that, if I remember right is 5 micron. Could not use to make domes as it is soft and flexible bit I sure could sure use to keep sand from sifting and substrate vacuums could keep clean enough for water flow. Yes 5 micron is fine enough to restrict water flow just on its own but I always overkill air flow for UG. If I did this for a 5 gallon scud think I'd probably use a Whisper 20 to drive the air risers which would be rated for a 20 gallon tank. Shoot, even using gravel as my substrate in my 20 gallon I use 2 separate filter plates with each plate driven by a Whisper 20 when one Whisper 20 is rated to handle the entire tank. I really DO think this could work well. Shoot, just looking at my main tank... when I do a major water change I end up with the air risers 3-4 inches above water level and they still push water. Using a Whisper 20 in a 5 gallon would equate to twice (actually may be 4 times) the air in relation to my dual Whisper 20 pumps in my 20 gallon using gravel. Considering half the substrate depth using sand I just can't see an issue. I just think that the air I would push would pull water through sand.

mts is malaysian trumpet snail. i should've used it with context from earlier lol

i'm convinced it might work now, i hope for the best!
after all there isnt much to lose, and scuds are pretty hardy as well

 

[TwoTankAmin]

The key to a proper;y function s under gravel filter, whether the traditional air powered or the pump powered revererse confidguration, is the size of the aggregate.

"Do undergravel filters really work?

It increases the amount of surface area available to the nitrifying bacteria, and it creates a constant flow of aquarium water over the colonized area. The most popular kind of biological filter is the undergravel filter. It is relatively inexpensive, reliable, and very effective."

The reason sand will not work is it will not permit adequate flow through a 3 inch bed. The sand filter many of us know is the one on swimmng pools. But the sand is in side a closed container and the pressure of the water flowing rhough it tumbles the sand so the grains are not all stuck together. There it traps debris rather than hosting bacteria. But if it was needed it could be seeded and used for that as well. All you need is an ammonia source and no more chlorine.

The ideal gravel of and under gravel is medium sized. Too small and it gets more sand-like and too large and the flow rate becomes to fast and the available surface area is reduced.

My first tank had an UGF but after a few months I converted it to a RUGF using a reversible flow powerhead. When I would remove the prefilter to clean it I usually lifted the powerhead of the uplift tube. This often dislodged it from the hole in the filter plate. Reverse fl;ow means there can be gunk building up under the plate that one will have to siphon out eventually. My tank was on an angle iron stand so I could look up through the bottom glass.

I decided to do this after several months and tI was surprised to see a few swordtails and panda cory fry under the plate and alive. This ended my time using under gravels. I had to empty the tank of everything to free the fish. I was only willing to do that once.

However, an undergravel filter is simply the best bio-media one can have. The next best is thing is a Hamburg Mattenfilter. However, a planted substrate is still the best filter an aquarium could have. However, not all tanks can be planted and not all fish keepers want to deal with live plants.

 

[jaylach]

The key to a proper;y function s under gravel filter, whether the traditional air powered or the pump powered revererse confidguration, is the size of the aggregate.

"Do undergravel filters really work?

It increases the amount of surface area available to the nitrifying bacteria, and it creates a constant flow of aquarium water over the colonized area. The most popular kind of biological filter is the undergravel filter. It is relatively inexpensive, reliable, and very effective."

The reason sand will not work is it will not permit adequate flow through a 3 inch bed. The sand filter many of us know is the one on swimmng pools. But the sand is in side a closed container and the pressure of the water flowing rhough it tumbles the sand so the grains are not all stuck together. There it traps debris rather than hosting bacteria. But if it was needed it could be seeded and used for that as well. All you need is an ammonia source and no more chlorine.

The ideal gravel of and under gravel is medium sized. Too small and it gets more sand-like and too large and the flow rate becomes to fast and the available surface area is reduced.

My first tank had an UGF but after a few months I converted it to a RUGF using a reversible flow powerhead. When I would remove the prefilter to clean it I usually lifted the powerhead of the uplift tube. This often dislodged it from the hole in the filter plate. Reverse fl;ow means there can be gunk building up under the plate that one will have to siphon out eventually. My tank was on an angle iron stand so I could look up through the bottom glass.

I decided to do this after several months and tI was surprised to see a few swordtails and panda cory fry under the plate and alive. This ended my time using under gravels. I had to empty the tank of everything to free the fish. I was only willing to do that once.

However, an undergravel filter is simply the best bio-media one can have. The next best is thing is a Hamburg Mattenfilter. However, a planted substrate is still the best filter an aquarium could have. However, not all tanks can be planted and not all fish keepers want to deal with live plants.

I understand that sand is denser and will restrict water flow but that same density should allow for a thinner layer of sand. With gravel one would want at least 3 inches but I figure on around 1.5 inches of sand due to the higher density.

Will the density of sand lower the amount of good bacteria? Of course it will but there will still be bacteria. The tank would also be planted with, probably, Anubias on rocks and/or wood along with water sprite as floaters and pumice rocks all of which will hold bacteria. I just don't see an issue as to good bacteria but we shall see.

Filtration would probably be better in my experiment if I used power heads instead of air but the scuds I intend are tiny beasties and will likely get through the sand and end up under the filter plates. A power head would kill them as they got sucked back out but using air would just toss them back into the water column.

Also a scud tank should not really need a whole lot of filtration as the only thing that needs taken care of is the beasties waste products. There is no such issue as left over food to deal with as they will colonize on solid foods such as chunks of pumpkin, apple peals... basically just about any solid veggie table scraps. Due to this there is next to zero excess food to deal with.

Shoot, I don't know if it will work but is one of those things that I think I have to try to find out. Like I said before, If it fails I'm not really out anything.

One nice thing about this kind of scud colonizing chunks of veggies is that it makes them easy to harvest. You weigh down the solid food with a fork or metal skewer and just shake them off into a net and transfer to the tank where they will be food.

 

[WhistlingBadger]

Sometimes you just have to try something for yourself and find out. Keep us posted!

 

[TwoTankAmin]

TYhe whole reason for having a UGF/RUGF is because of their bio-filtration potential. You do not need this by your own admission. It seems to me what you do need would be circulation rather than filtration. A thin layer of sand- say 1 inch, would host all the bacteria you might need/have since the plants will do most of the cycling chores. A tank of scuds is a pretty low bio-load.

The is no point to having a UGF as it will do nothing to make the tank healthier. In fact. the potential is it will have something go wrong and cause problems rather than doing any good.

In fact, I doubt you will need bio-filtration beyond the plants and substrtte, but you will need something to oxygenate the water and to provide a bit of circulation. An airstone, a small internal or hang on filter loaded for mechanical waste removal is about it.

I am a believer in the KISS theory--> "Keep It Simple, Stupid." Another was to say this is, "The simplest solution is usually the best one."
(KISS, an acronym for "Keep it simple, stupid!", is a design principle noted by the U.S. Navy in 1960.)

edited to fix typos

 

[StevenF]

I haven't doneThis, but I believe the solution to the undergraverl filter clogging is to not have anything in the sand bed. Instead put a divider in the tank create a small compartment for the pump. The only way for water to get past the divider is through a 1/4" gap between the bottom of the tank and the bottom of the divider. And then put you substrate on the bottom in both compartments. The pump would pump out the water in its compartment into into a spray bar(to aerate the water) into the main water compartmenwere the fish and plants are. The water wold then flow through the substrate back into the pump compartment.

IF the sand be starts to clog up with mule store up the substrate stick you water siphon deep tint the substarte to remove the excess mule. using screens filter fabric or anything else will eventually clog or get roots of plants tangled in it.

Note there are devices called sand filters that uses fine sand to filter water. you put a water drain a the bottom of a container and fill it with sand and then fill it with water to the top. If there is enough sand even the smallest particles in the water will not reach the drain valve on the bottom. Water utilities frequently use this. To clean the filter sand they reverse the flow of water through it. If you use a more porous material (gravel) it likely would not clog and still provide a home for beneficial bacteria.

 

[Back in the fold]

What about reverse flow ? Power heads that push the water up from beneath.

 

[jaylach]

What about reverse flow ? Power heads that push the water up from beneath.

Would make it impossible to clean any mesh used without breaking down the tank

 

[kiko]

well I'm the opinion that sumps are the best...
but if you did want an undergravel with sand why not use partitions?
let's say you have a 20" wide 20" deep
put like a glass/acrylic divider at 10" 2inch high fill one side with sand which isnt going to move...
the other empty side split it in 3 with the sides having soil for plants and the middle with sand with 3" tall dividers
put 2 plates angled downwards to the middle so whatever sand in it will just fall...
put a water pump with a tube connected before the "climb" with those little ball valves
the water pump has to be connected to the pipe in an angle...so it pushes the water through the pipe without getting sand in the pump
this will cause the sand to get sucked into the pipe without getting into the pump and pushed up with the help of air bubbles

once it reaches the top you need a T connection...one for air release...and the other side for "sand" return
and voilá you just created a sand waterfall aka sand ugf