I just used the basic inlet and outlet pipes the filter came with. I like the lily pipes; however, my tank is kind of built into my desk area so it would be hard to get a glass lily pipe off to clean it periodically. Yes, one CO2 setup for a 75 gallon is plenty, I just did two because I could go longer without having to replace the tank. If I removed the second one I would just increase the CO2 flow on the first one to make up the difference.
The factory outlet is more like a spraybar though right? Don't you get different flow patterns with those? I hear you on the cleaning though, those lily pipes brushes do require the pipes to come off first even then they can get stuck at times..
Is that 1500 LPH out of the box? Either way one filter should be more than enough to generate enough flow for co2 and dissolved ferts. You really don't need two filters as most of the filtration will eventually take place in the tank between the plants and surfaces mostly the substrate.
It sounds like you have nice aesthetics, why do you want to put more equipment in it. Just run the intake back left or right and the return on the same side but toward the front, so you get flow growing across the front and around the back.
1 filter would probably be enough but I am a big fan of redundancy, plus it also depends on the scape right? An open scape like
@woody123 has above could get flow with 1 filter, but with a very densely planted "islands" design with 2 incredibly dense back corners or very hardscape heavy scape I would be stressing if the backflow will manage to push the flow back through the back. Having the additional filter then would be great.
Filtration is not really a big concern for me to be honest, like you said, the substrate and plants will do good job taking the no3 out of the tank. Beyond that, I always just fill up 2 out of 3 media buckets in the filter with matrix leaving 1 for mechanical filtration. This also also one of the reasons why I want 2 filters, 1,500 lph out of the box is great, but it is still a manufacturing statement. It could be lower, or higher, in practice. 1,500 lph is also based on the default filter media, so as soon as I fill up it properly with media the flow will get hampered a bit right? Then we still have the oversized reactor, which, if I recall correctly can slow down flow up to 10%
I found this video from Green Aqua that does go into this subject, I love Green Aqua but I rarely take anyone's advice at face value, especially not on YouTube. Close to the end they talk about conflicting flow to create full circulation. In short, a hardscape heavy design could benefit from having 2 outflows pointed directly at each other. Meeting up in the middle and the opposing flow would then force the water to the back of the tank and so making a separate circulation in each half of the tank. In theory this also sounds this makes sense, but has anyone had any experience with this? Theoretics in aquascaping more often than not do not work in practice.
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Yeah as long as water is moving throughout all areas of the tank, so is your CO2. With 2 filters/intakes/output you can play around and see what works best for you. The only "wrong answer" is a setup that has dead spots where you don't have any flow. You might even have too much flow running both of those filters lol. You'll figure it out once you get up and running, definitely wouldn't stress it now
Unfortunately stressing and overthinking is in my nature.. In my previous tenure of aquascaping I also ran into a lot of small issues, which makes sense, since it is an ever evolving hobby and a lot of things to learn. Majority of mistakes also came with usual beginner choices of equipment. This is the reason I am troubleshooting the things I am fully sure about, this is the biggest tank I have worked with and it is the first thing people see when people come into the house. So I really want to avoid any mistakes. The first thing people should see when coming in the house is a beautiful scape not a scape that has uneven growth or an algae ridden scape.
I really just want redundancy in the tank, and I keep reading that 10 times overturn should be a good goal to help keep a clean tank. Livestock will be adjusted for flow heavy fish of course, though the majority will be cleaners anyway.