New member here, but have been reading for some time.

Looking to setup a 40*30*30 (L*W*H) tank with back sump and ATS integrated. Having read up the articles, I've settled on the following two designs but need some feedback from experienced members. Pump is to be Eheim compact 300, lighting to be HOB LED.

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The first design would be gravity fed, which would't allow flow adjustment while the second would and reduced flow for the output. hmm...