When sponge filter mods work better than expected!

[TOtrees]

I've had middling success with the dual sponge filters, the ones that mount to the side or rear glass with suction cups. I've found they are sort of "cross your fingers when you buy". Some of them have really good uplift, and others not so much. The good ones break up and distribute the air bubbles around the base of the uplift tube much like the jetlifters you'll see for mattenfilters. 

[IMO statement follows] For those who don't know, the single best way to optimize these side-mounted dual sponge filters (and their single sponge equivalents) is to set the top of the elbow that's at the top of the uplift tube at or just above the waterline. To the greatest extent possible this results in good horizontal flow across the surface of the tank, which in turns helps with vertical turnover tank-wide (as the horizontal surface flow hits the opposite side and partly dives down to the floor). 

One thing I don't like about these sponges is they are invariably sold with fine sponge (at least the selection here in Canadia is), which clogs faster and requires more work to clean. I've been wanting to retrofit these with coarse sponge, but standard sponge filters (like those from Hydro or Coop) won't work because the hole through the middle is too wide. And I couldn't find any pre-made to the right size on amazon or ebay. 

I did find a right-sized sponge block on amazon (dot ca), and bought it to try and see. I know I paid more than I should, but that's how trial and error works. Anyways, here's what I got, and I'm happy to say I'm thrilled and impressed with the result. 

I cut two square blocks from the end (2.75" x 2.75"), using the entire "height" of the block which was 4.7". The 4.7" height perfectly matches the height of the perforated sponge mounts on the filter frame, meaning they can be height-reversible. 

Here's a photo right after mounting/installing: 

I had to shave a bit of width off the side facing the glass, because it reached farther than the suction cups. So one down-side is that water won't be coming in evenly from all sides. But as the "fast" side clogs up, it'll balance out. 

This is a very mulmy tank that has been sitting empty for over a week, so please forgive the cloudiness. 

What really impresses me is the flow. With the higher porosity of the sponges, and the good design of the plastic frame and bubble-breaking features, and with the outflow adjusted to be right at the surface, here's how it performs in video:

It's not often you see any type of sponge filter kicking up debris on the floor, but it's doing that here. 

FYI I have enough sponge left over to cut another set of sponges for a similar sized filter. 

Thanks for reading/watching!

[TOtrees]

I dropped the water level in the tank, and you can see the water flow rate better. The fact it's able to lift the water this high is impressive. I've tried getting this amount of lift/volume with tubing and airstones, and it never works out. So kudos to the product mfrs. 

 

[jwcarlson]

I've got a very similar cheapy one from Amazon with fine foam and I'm shocked at how high it will lift.  The fine sponges do restrict flow a lot right away, but they're good to squeeze into new tanks for seeding! 🙂  

Yours is certainly moving a lot more water than mine do.  Did you just cut a small slot in the coarse sponge?

Edited January 27, 2023 by jwcarlson

[sanford]

Aquael Fan Filters use sponge as media. You can buy the sponges separately, they are relatively coarse and come pre-slit so that they fit on the sponge mounts.