At the time of my original filter review, I had not used the BioPlus Thermo 200 on a tank containing fish. I have now used it on both a tank containing only fish and a tank containing fish and plants. Keep reading for my thoughts on its usage in both scenarios.
Fish only tanks
Let’s start with its use on a tank with fish only. The BioPlus Thermo currently filters a 40g breeder. This tank contained a breeding pair of Amatitlania nanolutea, which have since spawned several times. At one point, only the female and surviving offspring occupied the tank. I removed the male because he was harassing the female too often post-spawn.
I think the filter is ideal for a tank containing non-breeding fish. However, I would not recommend it for any tank where you believe your fish might spawn.
There is no easy way to prefilter the intake, thus it’s not an ideal filter for tanks with breeding fish. You CAN prefilter it, but you’ll need to be creative. I have done so with a large filter media bag (see photo below). I inserted the entire filter into the media bag and zipped it as tight as I could. It’s a fine mesh media bag, which works great unless the top of your bag doesn’t come near the top of the filter. Otherwise, your free-swimming fry and/or juveniles that decide to explore and venture up into the water column might go down into the bag. Some of mine did, but they had grown to about 1/4 – 1/3″ by then, so weren’t at risk of getting into the fiter.
The filter is not perfectly round because of the shape of the media modules. This means there are small gaps where the media bag tightens around the filter, even when zipped tight. You might be able to use some really large bags, leave the top of the canister just above the water surface, and zip the bag just below the outtake. Note the filter is sitting on a river rock in the photo. This gets the outtake closer to the surface for water agitation. The outtake options do not include vertical adjustment.
What is the probability of really small offspring getting in between the bag and filter and then swimming down inside the bag? Low.
So where is the filter’s intake? Great question…and I have no idea. I have taken this filter apart and cleaned it dozens of times. I can discern no obvious intake location. Oase claims the intake is from the sides, but I don’t understand how it can physically do so. There are no openings on the sides of the media modules that allow water to access the media. There is a channel that runs up the center of the front of the filter, through all the media modules. Maybe I am just too dense to understand.
My conclusion and recommendation? I wouldn’t use the filter on a tank where you might have offspring unless you can creatively seal off the intake wherever it is.
Planted tanks with fish
Next is the scenario of using the filter on a planted tank containing fish. My recommendation would be to not use this filter on a planted tank either, at least not one that is fully planted. You can’t prefilter the intake (easily), thus you can’t prevent plant matter from potentially entering the fitler. Also, because the filter intake is presumably from the bottom, it will have a tendency to pull up soil and other particles that get disturbed near the bottom of the tank.
Before I began using the filter on the 40g A. nanolutea breeder tank, I was using it on a 40g planted tank. That planted tank contains a 3-4″ bed of aquarium soil. The filter was raised off of the soil about 2″. At the time, the tank contained a single female A. nanolutea and some danios. After just one week, the filter modules (sponges) were clogged, mostly with soil dirt, much dirtier than I like for them to be in such a lightly stocked tank. Again, the filter intake seems to come from the bottom, which suggests that the female was often stirring up the soil that was being sucked into the filter. Though I didn’t encounter much plant matter in the filter when cleaning it, there was often plant matter stuck to the bottom of the filter. That is good news. The intake openings are small, only allowing the smallest items into the filter.
Unless you want to clean the BioPlus more regularly than most filters, it’s probably not your best choice for planted tanks. It might work well for deeper tanks (24″ or greater) if you use the mounting suction cups or some other method to keep it well off the tank floor.