Undergravel Maintenance Frequency

I know not many people have experience with undergravel filters these days. My LFS rep gave me some advice I found surprising. He said, don't overfeed and just leave it alone. Keep doing water changes and vacuum debris without disturbing the substrate. Shallow vacuuming at most. He said the plants thrive on the mulm as it feeds them at the roots. Deep gravel vacuuming only once per year at most if I see blockages.

I like hearing this low maintenance recommendation. I'm a light feeder of a single Betta in a 2.5 gallon tank with what seems to be stable parameters now that I added oyster shells to the substrate. I'm consistently reading 0/0 NH3/NO2 with NO3 decreasing every day until I dose with easy green. I do daily water changes of 5-10%. I try to keep it around 20ppm NO3.

I don't see any build up in the substrate. Fish poop seems to be munched up by the mystery snail as soon as it falls. The bottom is clear and I see no blockage looking through the substrate from the sides through the glass. My tank has been running for 3 months and has very light algae growth. I test the water everyday while learning what happens when I do different things (water changes, easy green, co2). The snail and the betta seems happy...betta has a big personality.

As long as my water parameters are good, just keep the status quo?

 

Hi OhioFishKeeper
I ran an undergravel filter on a 2.5 gallon shrimp only tank and 22 gallon mixed tank for over twelve months. I had a tiny sponge filter as well in the 2.5 and a large sponge filter in the 22 gallon.

I am the kind of person that has 6 filters in most of my tanks that are 40 gallons or bigger. I know it’s to many filters in many peoples eyes but that is just the way I currently do things. As long as you know the extra sponge filter with the undergravel are from my personal choice of always having way to many filters in any tank.
I have kept betta fish in other tanks.

I think the advice you were given is good especially for the first 6 months while the 2.5 gallon tank is new and not fully established. I will add that in my opinion After six months you could consider vacuuming as often as you wanted?

I had no issues with the undergravel filters in the time I was using them.
I don’t think they are appropriate for plants?
I did have some day old endler fry swim into the gravel below the surface. I could see them against the glass half an inch below the top of the gravel.

When I removed the undergravel filters I decided they were not for me . Yes there was only a limited amount of gunk under the plate after more than 12 months but my issue was I had no way of knowing what was happening out of sight. For me the same air line that runs an uplift pipe on the undergravel might as well be running a sponge filter. That was my concussion. A sponge filter can be squeezed at anytime to know what is happening with it.

While I did not have a single betta with the undergravel I think the shops advice is good. You will not need to think about maintaining the gunk under the plate situation for 12 months is my guess.

A 2.5 gallon is probably not more than half an hours work to do that big clean once a year? / once in 18 months?

 

Hi OhioFishKeeper
I ran an undergravel filter on a 2.5 gallon shrimp only tank and 22 gallon mixed tank for over twelve months. I had a tiny sponge filter as well in the 2.5 and a large sponge filter in the 22 gallon.

I am the kind of person that has 6 filters in most of my tanks that are 40 gallons or bigger. I know it’s to many filters in many peoples eyes but that is just the way I currently do things. As long as you know the extra sponge filter with the undergravel are from my personal choice of always having way to many filters in any tank.
I have kept betta fish in other tanks.

I think the advice you were given is good especially for the first 6 months while the 2.5 gallon tank is new and not fully established. I will add that in my opinion After six months you could consider vacuuming as often as you wanted?

I had no issues with the undergravel filters in the time I was using them.
I don’t think they are appropriate for plants?
I did have some day old endler fry swim into the gravel below the surface. I could see them against the glass half an inch below the top of the gravel.

When I removed the undergravel filters I decided they were not for me . Yes there was only a limited amount of gunk under the plate after more than 12 months but my issue was I had no way of knowing what was happening out of sight. For me the same air line that runs an uplift pipe on the undergravel might as well be running a sponge filter. That was my concussion. A sponge filter can be squeezed at anytime to know what is happening with it.

While I did not have a single betta with the undergravel I think the shops advice is good. You will not need to think about maintaining the gunk under the plate situation for 12 months is my guess.

A 2.5 gallon is probably not more than half an hours work to do that big clean once a year? / once in 18 months?

I don't think it would even take 30 minutes. Just pull the plants, deep vacuum and replant. Just like my daily water changes...I take two big cupfuls out and then top it up. This is really easy and I'm enjoying taking care of the betta and snail.

 

At some time after 12 months you will have to pull the plastic filter plate out which requires a tank with no gravel so you can get the plate back in . All the water will have to go in a bucket along with the fish while all the gravel gets a quick rinse in conditioned water.
It will not take long the second time you do it but the first time it may take 30 minutes or more.

I don’t believe plants are going to consume the waste that will accumulate under the plate and deep in the gravel next to the plate that is difficult to vacuum successfully. Yes it may be possible to flush the gunk out from under the plate by using lots of air or a water pump but you will never really know what is under the plate without pulling all the tank apart, I suggest?

It may be 24 months before the fish waste builds up to levels that you find unacceptable or it might never happen. The point is you just don’t know what is going on out of sight .

I am not running down this style of filter. Some shops in my town still had them up until recently. They work well for what they do which is an excellent job of biological filtration. It’s the mechanical filtration that is a guessing game.

 

At some time after 12 months you will have to pull the plastic filter plate out which requires a tank with no gravel so you can get the plate back in . All the water will have to go in a bucket along with the fish while all the gravel gets a quick rinse in conditioned water.
It will not take long the second time you do it but the first time it may take 30 minutes or more.

I don’t believe plants are going to consume the waste that will accumulate under the plate and deep in the gravel next to the plate that is difficult to vacuum successfully. Yes it may be possible to flush the gunk out from under the plate by using lots of air or a water pump but you will never really know what is under the plate without pulling all the tank apart, I suggest?

It may be 24 months before the fish waste builds up to levels that you find unacceptable or it might never happen. The point is you just don’t know what is going on out of sight .

I am not running down this style of filter. Some shops in my town still had them up until recently. They work well for what they do which is an excellent job of biological filtration. It’s the mechanical filtration that is a guessing game.

I have a glass bottom, so I can take a look underneath to see if there's build up under the plate. You're right, I'll learn as I go and see what needs to happen. I had an undergravel as a kid, but didn't understand it back then...lost a lot of fish as a result I suspect. Now my goal is to allow this betta to make it to old age. If I can keep him going for 2-3 years, I'll feel like I'm ready to move on to greater aquarium challenges.

 

Undergravel filters are not very popular these days. When I started keeping fish six decades ago, there were no HOB filters, so undergravel filters and internal box filters were the only two choices.

Undergravel filters will eventually need cleaning. If your tank has only artificial plants, you can remove them and vacuum clean the substrate. If you have a planted tank, I would suggest getting one of the of bottles of sludge removed that contain falculative bacteria and enzymes to break down debris in the substrate.

If the gravel gets completely clogged and you have a planted tank, the only option may be to break down the tank completely. This is the reason undergravel filters are not as popular as they once were.

I still have one tank with an undergravel filter. I do not plan to touch it until my last fish in the tank dies. Then I will break down the tank only last time and dispose of it. After six decades of maintaining aquariums, I don't have many more years left in the hobby unless I keep a betta in a small tank when I go to assisted living.

 

Undergravel filters are not very popular these days. When I started keeping fish six decades ago, there were no HOB filters, so undergravel filters and internal box filters were the only two choices.

Undergravel filters will eventually need cleaning. If your tank has only artificial plants, you can remove them and vacuum clean the substrate. If you have a planted tank, I would suggest getting one of the of bottles of sludge removed that contain falculative bacteria and enzymes to break down debris in the substrate.

If the gravel gets completely clogged and you have a planted tank, the only option may be to break down the tank completely. This is the reason undergravel filters are not as popular as they once were.

I still have one tank with an undergravel filter. I do not plan to touch it until my last fish in the tank dies. Then I will break down the tank only last time and dispose of it. After six decades of maintaining aquariums, I don't have many more years left in the hobby unless I keep a betta in a small tank when I go to assisted living.

I hope you don't have to give up the hobby at assisted living. 60 years of fish keeping...it's who you are and you should keep it going.

 

I hope you don't have to give up the hobby at assisted living. 60 years of fish keeping...it's who you are and you should keep it going.

I started keeping fish when I was 10 years old; I got a 10 gallon tank for my birthday. Even when I went off to college, there was still a single pink convict cichlid that remained alive. My grandmother fed the fish and added water as needed. I did water changes and other maintenance when I came home on weekends or holidays. That fish went with me when I moved away to my first apartment and took my first job.

Over the years I have had multiple tanks including saltwater FOWLER and reef tanks. The saltwater got too expensive and too time consuming, so they are now gone.

A few years ago I got down to a single common pleco in a 29 gallon tank. I was most concerned that the pleco might die as I had a dreaded feeling that when my last fish died, I would not be far behind. So I got involved again. I now have a 55 gallon tank, a 40 gallon breeder tank and still have the 29 gallon tank with the pleco. He is about 15" long and shows no sign of imminent demise.

I am still in reasonably good health, but cannot do the things I used to do myself. Yesterday, we had a landscape company come to cut the grass for the first time. My wife and I have have been cutting our own grass since we purchased our first home over 40 years ago. Getting old and relying on others to do what you used to do for yourself is not fun.

 

I ran UGs under every sized tank you can imagine for a really long time. Based on that experience, I'll never do it again. They are great, right up until they are not, and then they are terrible.

As noted, you are eventually going to have to pull that plate and clean out the goop underneath it. That is the moment they stop being great.

 

When I did have one in a 20g, yeah, it was fine for a while, was a mess when you have to clean under there like everyone says.

Oh and I had a couple Kuhli Loaches that disappeared. I found them months later under the UG plate. when I just had to clean under there. not in the best of shape really but fed and alive.

it was enough for me to just give up on UGs overall, just easier ways to maintain clean water without letting detritus build up for months and months I think.

​

 

I have a 35 gallon hex that has an under gravel filter since 1995. When I water change ill vacuum 1/4 of the bottom next time ill do a different spot. My nitrites are 10 with zero problems.

 

I know not many people have experience with undergravel filters these days. My LFS rep gave me some advice I found surprising. He said, don't overfeed and just leave it alone. Keep doing water changes and vacuum debris without disturbing the substrate. Shallow vacuuming at most. He said the plants thrive on the mulm as it feeds them at the roots. Deep gravel vacuuming only once per year at most if I see blockages.

I like hearing this low maintenance recommendation. I'm a light feeder of a single Betta in a 2.5 gallon tank with what seems to be stable parameters now that I added oyster shells to the substrate. I'm consistently reading 0/0 NH3/NO2 with NO3 decreasing every day until I dose with easy green. I do daily water changes of 5-10%. I try to keep it around 20ppm NO3.

I don't see any build up in the substrate. Fish poop seems to be munched up by the mystery snail as soon as it falls. The bottom is clear and I see no blockage looking through the substrate from the sides through the glass. My tank has been running for 3 months and has very light algae growth. I test the water everyday while learning what happens when I do different things (water changes, easy green, co2). The snail and the betta seems happy...betta has a big personality.

As long as my water parameters are good, just keep the status quo?

If not vacuumed enough then of course the gunk will eventually build up... just like it would in any other type of filter that wasn't cleaned. How often and how deep is "enough" will depend on the particular tank and stocking/feeding levels. I've always found my smaller tanks gunk up quicker than the larger ones do, so I deep vacuum them more often. A Betta in a 2.5 is actually fairly stout stocking. I'd be doing a light vacuuming with my WC every week on that, with a deep vac every few months.

I like to base my intervals on how much junk I see being sucked up in the siphon tube when vacuuming. If it's a lot then I figure I need to step it up a bit.

If you keep up with it there won't ever be blockages or build up under the plates. At least I've never seen it and I've had tanks running UGF more than 10 years with no tear down. They are sitting on stands that have open access to view the glass on the bottom.

 

As you see in my picture, I have a black substrate. I put a layer of crushed oyster shells in and then covered it in black gravel. If I did do gravel vacuuming, I'm gone mix the colors up... Unfortunate. I'm trying to think of a process that might minimize this from happening.

 

I used nothing but undergravel filters for quite a while. In my opinion, they are great filters for fish only tanks, but not so great in planted tanks. The reason for this is plant roots get tangled in the grate making them hard to move, plant roots can restrict flow below the grate over time, and substrate fertilizers (like root tabs) get pulled up into the water column.

It may be true that your plants will like mulm build up under the grate, but that defeats the purpose of having an undergravel filter. It needs the flow under the grate to work properly. And, to keep the area under the grate flowing properly, you'll need to perform regular gavel vacuuming. If you're not going to clean your undergravel filter, you should probably add another filter.

 

I used nothing but undergravel filters for quite a while. In my opinion, they are great filters for fish only tanks, but not so great in planted tanks. The reason for this is plant roots get tangled in the grate making them hard to move, plant roots can restrict flow below the grate over time, and substrate fertilizers (like root tabs) get pulled up into the water column.

It may be true that your plants will like mulm build up under the grate, but that defeats the purpose of having an undergravel filter. It needs the flow under the grate to work properly. And, to keep the area under the grate flowing properly, you'll need to perform regular gavel vacuuming. If you're not going to clean your undergravel filter, you should probably add another filter.

I thought about setting a sponge filter in this tank instead of going with the old undergravel. Knowing what I know now, with the need for buffering, how can someone do it with a sponge filter? Seems like HOB, sump, undergravel, or canister are the only means.

My brother gave this tank to me 32 years ago. My ex-wife wanted to get rid of it, but I always kept it...knowing I would want to keep fish again some day.

I started with a 10 gallon with an undergravel at 7 years old...leaked everywhere...duct taped it as much as I could, but never stopped the leaks. Had some success here...probably a result of the forced water changes from the leaks.

Then a 29 gallon hex community with a HOB...great tank, but not clear like the undergravel. Then was gifted this 2.5 gallon for my room when I was 15 years old. At 18 years old, a 85 gallon reef tank with a wet/dry trickle filter sump and protein skimmer. Spent a lot money and lost a lot of nice fish. Converted the 29 hex to an undergravel fish only saltwater tank for copper quarantine. Left the hobby at 22 years old with 15 years of experience. 25 years later I'm back and learning a lot of thing I never knew before.

 

I thought about setting a sponge filter in this tank instead of going with the old undergravel. Knowing what I know now, with the need for buffering, how can someone do it with a sponge filter? Seems like HOB, sump, undergravel, or canister are the only means.

What do you mean by buffering? I think sponge filters can work just fine too.

 

What do you mean by buffering? I think sponge filters can work just fine too.

My pH was crashing before I added crushed oyster shells to the substrate. I don't know how you can have buffering with a sponge filter unless you make the substrate all crushed coral, oyster, or some other calcium rich substance.

 

My pH was crashing before I added crushed oyster shells to the substrate. I don't know how you can have buffering with a sponge filter unless you make the substrate all crushed coral, oyster, or some other calcium rich substance.

Ah, there are other ways to buffer your water. Regular water changes with an added buffer can do the trick.

 

I hope you don't have to give up the hobby at assisted living. 60 years of fish keeping...it's who you are and you should keep it going.

HA, I am also an old timer. I am 59 and have been in the hobby for 50 years...