Undergravel Filter: what doesn't leave the tank?

[Galabar]

Let's say that we have a UGF and nothing else for filtration.  We add food and that waste is brought into the UGF, breaking down into... something.  Is there anything in that food that would not, eventually leave the tank as, for example, nitrogen gas?  Could a UGF theoretically "run forever" without some sort of export?

Now, let's add plants to the mix.  Would exporting plant clippings be enough to allow the UGF to, again, "run forever"?  Would it be the case that there is some solid matter that would eventually clog the UGF (or have the level of the UGF start to rise)?

 

[Galabar]

With a powerhead running the UGF, you (probably) wouldn't see anything build up under the plates.  Also, my understanding is that gravel vac'ing a UGF is counterproductive.

I'm wondering if they can be run "forever" without gravel vac'ing, or if there would be some build up over time.

[Andy's Fish Den]

On 5/15/2023 at 9:32 PM, Galabar said:

With a powerhead running the UGF, you (probably) wouldn't see anything build up under the plates.  Also, my understanding is that gravel vac'ing a UGF is counterproductive.

I'm wondering if they can be run "forever" without gravel vac'ing, or if there would be some build up over time.

Even running a powerhead on the riser tubes, you will get a build up under the plates. I haven't run a UGF in year, but when it was popular back in 90s I had one in a lot of my tanks and had several with powerheads, and I still got build up. Now, maybe I didn't have a strong enough powerhead? But, I had a 125 with the biggest powerhead made at the time on the two corner riser tubes and there was still build up under the plates. 

There will be areas of the gravel that will fill with waste, whether its uneaten food, fish poop or whatever, but it would take a lot to completely clog the gravel bed and thus the filter. It's no different than in a tank without a UGF or even bare bottom, you will find areas in the tank that waste will build up due to dead area of flow or around rocks, wood, etc. It will be the same and build up in the gravel under those things, the only difference is that the flow of the UGF will pull it down into the gravel. 

[Chick-In-Of-TheSea]

Having run a UGF for about a decade, I will join the pro-siphoning team here.  You want beneficial bacteria in the gravel and on/under the plates.  That's the goal.  Not mulm.  Gravel vaccing should be a normal part of changing water.  The slots in the plates allow for small mulm to drop down to the glass.  Likewise, that mulm can come back up through the plates when you siphon.  Not all of it.  But enough to ensure your undergravel filter continues to run effectively.  Routine siphoning is also important because in the event of a power outage, you don't want the fish sitting in the tank with all of that waste and no filtration.

I would not suggest a UGF for a planted tank.  For one, you'll want to be siphoing.  But also, the plants need the nutrients (ie: root tabs, etc) to stay in place for their roots to take up.  With the ongoing water circulation under the substrate, that is not feasible for plant health longevity.  If using plants, go with rhizome plants that do not get planted: java fern, java moss, buce, anubias. Floating plants are an option, as well as stem plants that can be floated around and feed from the water column (ie: water sprite, anacharis, hornwort, etc).

Edited May 16, 2023 by Chick-In-Of-TheSea

[ktk4beees]

UGFs have their beneficial uses and as far as I can tell are really no different than a deep substrate bed just different. I started my aquarium career with hydroponic aquariums. In other words, an ecosystem with the fish supplying the nutrients for the overhead plants to thrive. 

I live in a fairly remote Mountain Valley right at the 45th parallel. It gets cold here quick and some plants require longer to produce than we have weather to support them. So, I went to growing some things indoors. We are also really dry here with low humidity so the indoor idea was born of needing to up the humidity in my environment also.

The way it works is there is just a basic pump sitting on top of the UGF. it takes water and nutrients from the UGF to the plant or plants sitting in a deep container over the tank. Sort of like a sump in reverse. I will put a picture of my 2 year old tomato that is still producing. The water goes up and the porous rock holds the plants roots and washes the water then returns the water to the tank. Works for me really well and in that tank I never have algae issues. I have had a variety of fish in the tank over the years, all got too big and had to be moved to other tanks so that tells me the environment in the tank is healthy. 

 

[Chick-In-Of-TheSea]

On 5/16/2023 at 1:20 PM, ktk4beees said:

growing some things indoors

Pretty cool setup! That plant is a beast! Lol

On 5/16/2023 at 1:20 PM, ktk4beees said:

UGFs have their beneficial uses and as far as I can tell are really no different than a deep substrate bed

A deep substrate bed has the presence of aerobic (upper layer) and anaerobic (lower layer) bacteria. A UGF setup has only aerobic bacteria because of the water movement- oxygen being part of the water molecule prevents anaerobic bacteria from colonizing.

Edited May 16, 2023 by Chick-In-Of-TheSea
Spelling

[Chick-In-Of-TheSea]

Beautiful tank @Pepere! 
Terra cotta pots could work too, or the Easy Planter!

[ktk4beees]

On 5/16/2023 at 1:40 PM, Chick-In-Of-TheSea said:

Pretty cool setup! That plant is a beast! Lol

A deep substrate bed has the presence of aerobic (upper layer) and anaerobic (lower layer) bacteria. A UGF setup has only aerobic bacteria because of the water movement- oxygen being part of the water molecule prevents anaerobic bacteria from colonizing.

I have a layer of smooth black gravel then a layer of Florite Black Sand on top to create a "real" substrate for all the bacteria over and above what is under the UDF. I have a colony of Pumpkin Shrimp, Blue Black Half Moon Dumbo Eared guppies (such a big name of a small fish), a dwarf Pleco and a host of snails contributing to the Beast on top right now. They seem to enjoy their home and I got that tank to 167 TDS with a PH of 7.2 for the time being. Also the hang on back filter and a bubblier help with the water movement when the tank is not cycling. Then there is a lot of water movement as the cycle drains about 1/4 of the tank when running. There is a warning sound when the pump is about to go into operation and it is interesting to see even the snails head to the bottom or at least lower in the tank when it sounds. It is quiet enough I do not notice it anymore unless I am working on the tank or plant.

[ktk4beees]

On 5/16/2023 at 2:02 PM, Pepere said:

I dont think I will ever start another tank without ugf plates in it.  They are simply too cheap and add too much surface area for beneficial bacteria to grow to not use in my estimation, and excellent to have in case of a power outage as a simpleair pump keeps them going.  Not much electricity needed…

If one feels it is hurting plant growth, you can always shut off the air flow.

 

they are not much for flow to keep co2 bubbles suspended or for mechanical filtration, hence my internal filters…

 

I am about to try a cannister filter and spray bar and pull out the internal filters.  The internals work fine, but they arent much to look at, and they need to be cleaned weekly.  I am hoping for better mechanical filtration and flow with the canister and less frequent maintenance of it…

 

time will tell….

 

I am about to set up a new tank as soon as I get my water situation under control. A 20 gallon long with a UGF and a hang on back canister filter with spray bar or dual flow. Not sure which flow I want yet. That will depend on which fish I can handle with my water issues.

[Galabar]

It's funny.  I could have just kept using them from the 70s and avoided a lot of additional equipment.

By the way, a saw that Sicce Shark sticking out in the upper left of that tank.  I love that thing! 🙂

 

[Galabar]

For the Sicce, I leave the biological media in the top compartment and, for the bottom compartment, I have a very small sponge and then filter floss with some activated carbon.  I just take off the bottom compartment off, toss the floss and carbon, add some more, pop it back on and I'm ready to go.  The sponge doesn't take much cleaning because it is so small.

 

[Galabar]

I'm thinking my next tank (I just purchased a 30 gallon) might be a Sicce pointing its nozzle output into a downtube for a UGF.  Massive biological filtration without any buildup.

This isn't anything new (Reverse-UGF).