Matten Filters And Airlifts

[Popster]

Hi,

So I have decided to use corner Matten Filters on all my Guppy breeding and grow tanks. In this process I have been researching airlifts and indeed built one from YouTuber "Terrarienbau Berlin" informative video.

So the one I built is for 20mm OD PVC pipe and is 30cm (12") high tip to tail. I deliver circa 150l/h air to it (pump spec's, will still measure) and I am getting a flow rate of 400l/hour (105g/hour) which I think is amazing. There are 24ea, staggered and spiraled 1mm holes in the tube which is sealed in a "pressure chamber".

So as a person who hates noisy aquaria, with the outlet above water height it is a little noisy. I then dropped it to have the top of the outlet just below the waterline, dead quiet. But as the water is now being pumped into water there will be resistance to flow and the flow rate must be impacted.

What is the conventional wisdom, outlet above the water or below the water?

 

[JayH]

I have a Jetlifter from Swiss Tropicals. Same basic Czech airlift design as your DIY version. I found the best flow was with the lower portion of the outlet just a couple mm below the water line. The falling water noise disappeared completely.

I think optimum flow rate is going to be with the outlet right at the water line. It has to lift the water to get it above the water line and that's going to significantly impede flow. Lifting the tube makes this clear as the flow obviously reduces and then stops entirely as you raise the tube.

To me the quietest position was with the outlet positioned so the water line was just about half way up the outlet. This allowed the bubbles to burst inside the tube, containing a lot of that noise, and eliminated the waterfall noise. Logically, this should also be very close to the best position for flow as well.

Was it difficult to build the airlift? I thought quite a lot about doing one myself and did a fair bit of research on optimum hole diameter and required air pressure. Finding all the necessary parts turned out to be an issue. Ultimately it looked like it would be cheaper to just buy one. I was intrigued by the idea of experimenting with it and may try building my own if I need another in the future.

 

[jjohnwm]

Would the resistance to flow you mentioned be countered by the need for the above-surface to lift the water higher? I have no idea, but it might be worth examining.

If your measurement of over 100gph is accurate, that is quite astonishing. I use these filters a lot, almost always powered by air, and often have 4 or even more lifts per Matten sheet. I usually situate the elbow at the top so that the normal water level is at the midpoint of the opening in the 90, thinking it would be the best compromise for maximum flow...but it's noisy. My tanks are in the basement so the noise isn't an issue for me. Quietest operation seems to be with the 90 completely exposed above the water. I am looking forward to more info and opinion on this.

 

[Popster]

Dead easy to build. The hardest part is catering for my OCD and drilling the holes in a perfect matrix .

So in your case you would use for a smaller unit like mine. 3/4" OD pipe, a 1" straight connector and a long elbow connector. I have found that the 90 degree is most convenient from a space perspective, but the best flow is through larger radius elbow.

So the trick is to seal the 1" straight connector tube around the air holes. This ensures that the air is forced out from where you want. Effectively one is creating an air stone ring outside outside of the water pathways removing all obstructions. We also don't want the air tube to go down inside of the pipe, we are merely obstructing the flow.

Pic of the PVC Elbows

Pic of the "pressure chamber"

Pic of the assembled unit

Video of the operation

 

[JayH]

I'm not exactly OCD-ish but I do like to do things proper and would never be happy with holes that were too large or in a haphazard pattern. I was planning to do a pattern so there would effectively be a wall of bubbles going up the entire inner perimeter of the tube, overlapping the horizontal position of the holes by staggering the vertical position. I'm sure you accomplished something similar with your spiral.

Finding a drill bit small enough was one of the issues that held me back. The biggest thing was getting a sweep in the right size. Most of the plumbing parts have tight 90s. You can get sweeps in electrical parts, but there's no call for conduit that small so, again, virtually impossible to find in the size needed. I'm sure if I'd searched long enough online I'd have found somebody selling what I needed, but the whole thing was rapidly approaching the point of diminishing returns. Buying one for $10 seemed the better option. If I needed five or six of them I may have pursued the DIY approach a bit more.

I was very impressed with this design when I first saw it. It's one of those things that you see and wonder why somebody didn't think of this decades ago. It's brilliantly simple and elegantly solves several problems.

You did an excellent job on yours. Looks very close to the professionally manufactured one I bought. Awesome flow in the video.

 

[Popster]

Pic of Drilling Template

I am going to make a couple of these so the first point of order will be to make a mild steel drilling template as this removes 60% of the construction time.

It is in mm as we are metricated here but you will get the idea. As you can see not one stream of bubbles affects the other.

It will almost appear as if the finer the bubble stream the more water is lifted and the less noisy it becomes. So before setting up for "mass production" I am going to try a 0.8mm drill bit and lift the hole count to 36 on the basis that this is the same area as 24 x 1mm. I don't want to mess with the amount of air, it appears correct based on the excellent flow rate. I just want more bubbles to see the effect of this.

Another thing I may consider is a technique stolen from the DIY camping alcohol stove fraternity. They drill the holes (typically 0.8 amd 1.0mm) as the jets for the flames. They then slowly angle the drill to give a "direction of flow", this creates desired vortexes. Now I am not sure that I want a vortex but having the air already directed towards the surface has to be better than it coming our at 90 degrees. I know this is real pedantic but may be the next slight improvement to the design.

 

[JayH]

Have you looked into optimizing the size/number of holes based on the pressure in the air chamber? I started looking into that and was surprised at the amount of air that can go through a 1mm hole at even low pressure. If you don't keep the air flow below the threshold of what the pump can provide there won't be even pressure all the way around the tube and you'll get an uneven pattern of bubbles. I had found some resources online that were quite helpful, though they asked for some parameters where I just had to guess because I wasn't sure what they were asking. Unfortunately, I didn't bookmark any of these and it was long enough ago I'll never find them in my browser history.

I initially had purchased a small Tetra air pump but it didn't provide enough air to drive the Jetlifter properly. Then I went the other direction and got a much larger one intended for "deep" water use. I figured the pressure it could maintain would be a good thing. It provides more than enough air for one Jetlifter.

I love your pattern. That's exactly the type of thing I was shooting for, where you get essentially a solid wall of bubbles with just a tiny amount of vertical space offsetting them.

On the angle of the hole, I wonder if there would be a way to use that to coax some of the bubbles further toward the center of the lift tube. Maybe mix up the angles to create more of a jumble of bubbles. That kind of goes against the wall of bubbles idea, but bubbles rising through the entirety of the lift tube seems like it would be the most efficient in terms of moving water. This is probably gilding the lily since enough air pressure should shoot the bubbles into the tube and cause them to bounce off each other already.

 

[Popster]

I suppose the theory would be that the smaller hole would carry more velocity and should expel the air further into the tube.

Is 1" foam suitable as a corner Matten Filter in smaller tanks or must it be 2" thick.

 

[JayH]

According to the Swiss Tropicals web site, 1" foam is not suitable for vertical use. 1.5" foam is okay for tanks up to 5.5 gallons. 2" apparently has enough rigidity to use in most any size tank or sump.

 

[Popster]

OK so there goes my new purchase, one square yard of 1" thick. I am sure that I can find another use for it.

Will go buy the 2" tomorrow.

Could not get 2" from the fish store so I bought the 1 37/64" or 40mm. I made a straight Matten for my current fry tank and two corner Mattens for the larger grow out tanks. Really worked out well.

I have had a small sponge filter in the fry tanks for 2 months now, along with a small corner filter. When I squeezed the sponge filter to impart the bacteria to the new Matten sponge basically very, very little came out of the sponge filter. The filter was clean. As previously stated I have been over feeding so one would have though that the filter would have been all gunked up. On the contrary the small corner filter I had in was gunked up and you could clearly see that it had really been working.

I am now a concerned about the effectiveness of sponge filters. Someone help please?

 

[bigdreams]

Very impressed w/ your DIY jet lifter. I definitely don't have the skills/machinery needed for that...

I have a mattenfilter in my sump... 2 3" blocks of Poret foam from Swiss Topicals. love it. It's insane how much mulm these things generate after a while ... one benefit is fewer filter cleanings... in fact, I didn't clean my filter for almost 2 years.. then felt like I had "to do something" and squeezed them out. instant mud soup. I do wonder if these things cause nitrate factories. Seems like they would have to... anyway, my tank seems to be ok. now almost 4 years old.

 

[JayH]

I am now a concerned about the effectiveness of sponge filters. Someone help please?

My guess would be it's a matter of flow. The smaller commercial sponge filters have never seemed to me to have much flow. They either just use whatever bubbles out of the end of the air hose or they have air stone that blocks about two-thirds of the uplift tube. The Czech lift tubes you built should solve these issues as long as you have sufficient air going into them.

The fairly small sponge filters I've had in the past would make a five gallon bucket look like it was filled with muddy river water when I cleaned them, so I know the concept is fine. Perhaps your corner filter had better flow and sucked up most of the muck, leaving nothing for the small sponge filter to deal with.

If you pump enough air through those lift tubes you'll be very happy with the performance of your Matten filters.

 

[Popster]

So the matten has been in my fry grow out tank for 4 days now. Yip not long enough given that there was little to no starter culture fro the matten filter.

The tanks is real smelly (I do have an over developed sense of smell which is problematic), I am changing roughly 30% water per day but still smelly. I did notice that the smell predominately emanates from the the area where the matten filter is. Is this common?

PS: Cannot seem to upload pic's