discussion on biomedia...

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Magnum Man

Fish Gatherer
Jun 21, 2023
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Southern MN
I've been doing this a long time, & given it much thought, & practice over the years... I doubt many would argue that more surface area is better on bio media sources... but I just saw some listed for sale, that I feel isn't a step in the right direction... I used to use porous lava rock, like you would use for a gas grill, or gas fireplace... & was happy with that for years, until I shut my tanks down ( about 20 years ago ) the lava rock was covered in bio slime... I'm sure all the holes were full of beneficial bacteria, however, from what I could see, the water could not get into the pores... in effect, the rocks could have just as well been smooth round river pebbles... when I was shutting down my tanks, sump systems were the rage ( mostly for salt water tanks ) & most of the media was like wiffle golf balls... you don't see that kind of media much in the hobby anymore... however a hollow ball full of larger holes ( large enough to not blind over, so water could flow through them ) has almost twice the surface area of a solid round ball ( or rock )... getting back into the hobby a year & a half ago... ceramic seems to have replaced the plastic biomedia... & I see Seachem offers a porous ceramic media for the filters, & I see similar, in both the Aquaclear 70's I have, as well as the Tidal 75's I have... I don't see any advantage or even less than those old lava rocks I used, as the pores are smaller, that what was in the lava... I've personally been using little ceramic tubes, with 1/4" center holes since I got back into the hobby...

so I'm a little curious why the wiffle golf balls fell from grace??? is it because they aren't natural ( the filter boxes are plastic )... there has to be al least twice the useable surface area for beneficial bacteria, as long as the holes are big enough they don't blind over...

I have a 250 gallon tank I'm hoping to set up this year, & I've been seriously looking at filling the filter chambers with the plastic wiffle golf balls

anyone want to dive in, with knowledge or practical experience...
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I believe the plastic biomedia like the wiffle balls do not have enough surface roughness to retain all their bacteria colonies when the biomedia is serviced. Due to flow issues seems like it is a bit of a packing problem, you want a large surface area but you also what good water flow.

My personal experience is that the hollow cylinder ceramic media work well. You get good water flow though a space packed full of media, there is enough surface roughness so the colonies are not easily sluffed off. I use some round ball ceramic media as well but I find the hollow cylinders seem to keep the flow better.

I think vesicular lava would work well, but to prevent tight packing of the media you would want to make sure that most of the stones are the same size, so that the smaller stones do not fill the voids between the larger ones. In general, I would expect your biomedia overall to work better if the media particles are of similar size otherwise maintaining high flow through the media might be difficult as it settles.

Just my thoughts no research.
I could be wrong, but I think the bacteria has adhesion, as it's also on the glass, and all the tanks surfaces... I would suspect you are correct on trying to have similar sizes for flow... also golf ball size would likely be too big to get maximum efficiency from a typical hang on back filter... but a bio media of similar construction but of a smaller size 3/4 inch diameter might be nice???
Hello Magnum. Since beneficial bacteria grows on all surfaces inside the tank, I question the need for any type of filter media. I stopped using mechanical filters and just increased my water changes to half every few days to a week. I'm supplementing the water change routine and use the Chinese Evergreen to use the nitrogen produced by the fish. The combination has resulted in nitrogen levels below 20 ppm when I tested the tank water one time a long time ago. With such an aggressive water change routine, I doubt that nitrogen would even register on a test. My tanks have a lot of local rocks and driftwood, so there's plenty of surface area for bacteria. Over the years, I've certainly saved a lot of money on mechanical filtration and replacement media.

plants do make a big difference... I can't help it, I like a lot of water flow, and most of my fish , he said currently ( catch the joke ) are river fish so they like the flow as well...

I've not been lazy, but I'm a couple water changes behind, because of refilling my 45 gallon ( used up all my RO water ) for a week...

but having the plants, & all that mechanical water movement... the fish are still looking good...
I could be wrong, but I think the bacteria has adhesion, as it's also on the glass, and all the tanks surfaces
I believe you are right, but a simple wipe of a cloth over the glass will remove the majority of the colonies on the glass, whereas with a porous media even if roughly handled you have refuge spaces where removal of the colonies can be difficult. I don't service my filters much after going to the canisters and foam filters but when I used the aquaclears I was often rinsing the biomedia.
Hey Magnum. So, tell me, why the Reverse Osmosis water? Is your tap water too high in minerals. What have missed in your posts that you need RO water?

we are in Southern MN and have some of the hardest water in the country... a long time ago, the house was hooked up to a whole house softener, no well water lines in the house, or big rusty stains in a week, in the sinks... so my only original option was house softened water, which was hugely alkaline... I recently added a saddle valve for a 1/4 inch poly line, before the softener, and ran that over to my aquariums, and RO unit... the RO unit was burning through the softener salt, & to add to tanks, like my cherry shrimp and live bearer tank

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