Need advice on possible over-filtration

[GinnyFinny]

I chose a 20-long tank because one can be creative in aquascaping mainly. I've used in the past (& still have) a AquaClear 20 & just bought a Fluval (AquaClear) 30. I started out the 20-long tank using the Fluval 30, with the flow control at maximum. I know it's rated for 150 gph, but I'm really tempted to add to my tank the AquaClear 20 (100 gph?), setting both filters at their MINIMUM out-flow. I assume the gph rating on these filters is based on maximum flow from the adjustable lever on top.

My concern is too much current with both filters running. This idea was put in my head by a LFS that has a great reputation. I don't want my fish being pushed all around the tank. It's just that the Fluval/AquaClear 30 doesn't seem to produce the flow that I'd like - but forget me....it's all about the fish.

I'm hoping I get encouragement and the push I need to add the AquaClear 20 to the 30 and see how it goes. Even though the system is just over a month old it's heavily planted with small plants for now. I have 12 Cardinal Tetras, 6 Endler's Livebearers, & 16 Amano Shrimp.

Even amongst the readers of this post there will probably be wide difference of opinions. One other thought that came to me just now was the possibility of buying one AquaClear 50. Could that make a difference in the current created by 2 filters as opposed to 1 filter?

You guys are awesome with varied opinions, a wide range of levels of expertise, & years of experience.

 

[Squeaker]

I would give it a try. But only on a day where you can monitor the tank. My Endler's seem to love the bubble bar, I catch them riding the current. Lol...

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[BBradbury]

Tank Filtration

Hello Gin...

I would use the larger of the two and follow a sound water change routine to keep the water free of dissolved wastes. This is the most important thing. The filter's main job is to keep the surface moving to mix oxygen into the water and aid in the removal of carbon dioxide. This process is called "gas exchange". The filter does a poor job of keeping the water clean, because it can't remove the toxic water and replace it with clean water. This is why you must remove and replace large amounts of tank water regularly.

B

 

[Fresh2o]

I run 2 AC50s on a 20g long for the last couple of years. Yes, overkill. There is a lot of flow (15-20x) but this is in a heavily planted tank with a bunch of nano fish. I do have problems with some of the smaller plants getting uprooted. I blame that on the burrowing snails. The fish are not affected by the flow. I believe the plants and dećor break up the flow. Could I have used just one? Certainly.
*** I do want to stress that over filtration is NO SUBSTITUTE for the amount of water changes one needs to perform.***
In my situation, I like the idea of having redundancy in the event of one the filters fails (no likely as these are very reliable filters). I like the idea of having the space to house additional bio media for a quarantine tank. Most of the time in the second filter I use floss only or floss + sponge + ceramic media. I like the ability to be able to replace or clean the floss on a frequent basis. It traps a lot of physical waste and being able to get that out of the tank is a plus.
In your situation, I would run both the AC20 and AC30. You can always reduce the flow as needed. Just keep an eye on the fish.


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[Wy Renegade]

I've run 10s, 20, and 50s, and I also do not believe that you will have any issues with the fish. The plants may be another issue, as they have no ability to move out of the current created by the filters - however I would think that would also be a minor problem and easily alleviated by placement of the filter.