Penguin/Bio-Wheel 150 Mid-Level Strainer Setting

[otakuoverlord]

Hi- first-time aquarium owner with a basic question... I have an 18 gallon tank and it's tall (imagine two ten gallon tanks stacked atop each other) and i am using a 150 as my primary filter. It has a mid-level strainer with an adjustable intake, and I have NO clue as to what it should be set at!

Full open? Closed? Marineland doesn't say anything about what setting it should be at. I don't want to siphon water ONLY from the middle, nor do I want to take it only from the bottom... Right now I have it halfway open, and I don't know which way (positive or negative) I am impacting the filtration. Advice would be most appreciated.

here's a bad ascii image of my tank setup.

|------------waterline
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|Midlevel Strainer is here
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|Bottom siphon is here
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|xxxxxxxxxGravel

[perle]

Honestly it probably hardly matters, but I have one of those and like it to intake mainly from the bottom and only from the mid a single notch or so. This way the water circulates from the bottom up to the top and back down, the maximum amount (at least in my imagination).

The fact that you can close the middle intake completely but can't close the bottom one at all ought to give you a hint.

~perle