***This is just my experience***
So like most folks getting into reefing, it’s all about trial and error and experience pays off, even in this topic. I have a custom made 150 gallon acrylic drop down tank that I designed. Figuring out proper water flow is tricky to say the least. Like most people, we like to enjoy the natural echo system (and show it off) without the introduction of ugly pumps,wires,tubes,strainers, etc.
On a brand new tank, this is very evident and somewhat discouraging. As the tank matures and you get adjusted to the noise and looks of your equipment that run your system, you forget that most new visitors you introduce to your system are not adjusted to this. I am constantly upgrading my pumps to make it quieter and less obtrusive while not sacrificing the necessary water flow needed.
it seems like “the necessary” water flow is impossible to suggest to anyone and the general consensus is “avoid dead spots, don’t let it damage your corals, and don’t let it rearrange your landscape”.
Of course, with a new tank, some of that info is mute and almost impossible to do ahead of time until your tank matures and you add live stock.
my systems water flow consists of the return pump (4 outlets on one side for the top half). A closed loop for the bottom half of the tank (4 outlets on one side). One ice cap 1k gyre on the top upper side where I have mostly open water and is 40” deep.
Although I have a lot of water flow and my corals and live stock are thriving, I still have to do a lot of maintenance to keep it thriving that could ease the work load if I had more water flow.
Almost everyday I take a turkey baster and clean my rocks/corals off to keep sediment from becoming an issue and gravel cleaning with my water changing schedule.
I have made some changes which included replacing the super loud max pumps on the return with a apex cor 20 and my closed loop blue line pump with an apex cor 15. This allowed me to adjust the flow rate or in the case of the closed loop, have it set on different flow rates through out the day.
my next upgrade is to get the new maxi fx330 gyre for both ends of the tank and remove the ice cap to see if that will help with any current low flow areas to help breakup sediment deposits on my rock work.
If I had any suggestion “with my limited experience” for new reefers when it comes to water flow, try to get pumps that you can adjust flow rates and be prepared to adjust or add more. There is no reason to go out and buy more than you need right away. Just use common sense. You can always use something simple like fish food to see what your water flow is doing