I've been contemplating recently for a reasonably priced canister filter that will support a 75. I've been looking at the following, Fluval 406, Aquatop series, Eheim 2217 and Rena xP filters. I can't come to a decision.
I use a Cascade 1500 in my 72 bow. I just have a thumb strainer on the outlet (to keep loaches from swiming in!) It works well and definitively doesn't provide too much current (it's supposedly rated for a 200 gallon tank). Just in straight numbers, I'd say the tank should be turned over 2 - 4 times per hour, but there's debate about that.
My old cascade 700 just wasn't big enough and there'd be food floating in the water hours after I sprinkled it in... The 1500 is just perfect
That's almost like asking a group if Ford or Chevy is better but I will give you my spin!
Much of my filter decision comes from looking at the tank and asking if the filter is doing what I need. If the mechanical is up to what I want my water to look like, fine. If the filter is keeping all the ammonia and nitrite converted with slack for growth and any small mishaps, that is all it can do on that front. Then comes the decision of getting enough water moving. Fish only reguires only that the debris is moved around to suit you but with plants there comes the extra need to move any CO2 around to all the plants in an effecient way. Sometimes that takes more current but not so much it is tearing leaves off the plants.
I can really only speak for the Eheim and say that the 2217 is my choice of canisters in the older classic lineup. I use a single 2217 on all my 75 gallon tanks and am very happy as I find it has plenty of the two main filter functions (mechanical and bio). As I add more planting and get thicker plants, I have seen spots where I needed more waterflow. For that I find powerheads are much easier to fit to get the flow where I want it rather than just dumping it in with a more powerful and expensive filter. Powerheads are my choice as they are versatile enough to fit most anywhere and do many different jobs.
I suggest getting hands on with a canister of each type and see which media setup you like. Some of those you mention would not suit me for ease of cleaning and adding/changing media to suit as the situation changes. Tanks rarely stay the same for long and I like equipment that is flexible as I need it.
Flow and gallons per hour will vary with each tank and what fish or plants and the number. I find the Eheim specs fit for me.
I have used a lot less than a 5x turn over rate in my tanks. However, after going bigger, I have to say, I am a big fan of more flow. I would do at least 400 GPH or so (rounded up the number in case of inline, etc). I would consider going even bigger than that as well, especially if you are going with CO2. Not researching each one, I know it puts a few of them out of the running. Does that mean your tank will not work with less, not at all, I have had great tanks with less flow than that. The investment is cheaper now than buying a second filter later, be it in conjunction with the filter you buy, or selling it down the road and upgrading.
I'm new to planted tanks and I find differing reasons here on this forum than I found on fish only forums. But it is always a big discussion of what turnover amount is needed to make a tank work. There are people who want a lot of equipment and those who don't. Both work so it is pretty much a personal decision which type you want to be. There are those who are sure their tanks work due to the amount of filtering they use. But then there are those whose tanks also work as well with half the filtering.
Personally, I hate equipment. I buy large enough to assure it will work and then never add more until I see a need. My fish have all been thrived and bred well enough to suit me. I'm hoping my planted tanks will be as much fun but there are no guaranteed success paths.
That definition sounds right to me. Flow to me is somewhat different at times. If speaking of the water at the outlet of the filter I would say they are the same thing but if speaking of how the water moves around the tank it can be quite different. Each tank will be different and have different needs as well. If you use large stuff like a stump or large rocks, the flow in the tank will be different than a bare tank. With plants and adding CO2, it is good to make sure the CO2 is spreadevenly around all the plants. This may require more flow. My spin-- others may vary.
Filter-wise I wish I had more. But I also have a 120GPH powerhead and a Koralia 750 to push water around.
If you're planning on going "heavily" planted in a 75, I would go with 2 canisters. My 2217 is struggling to keep up. I also have a high bio-load with all the fish. I clean it out every 3 months and its NASTY. Shows it does it's job, even with a lower flow rate.
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