flow for closed loop

[sphelps]

Many LPS do better in lower flow, many if subjected to SPS type flow requirements won't open and expand fully and do poorly as a result. With a closed loop you can point flow upwards towards higher portions of the rock work that could contain SPS and LPS will do well below. Also keep in mind if your pump is rated at 3600 GPH and you run it through an OM and typical tight closed loop plumbing you'll probably see closer to 2000 GPH if that. Closed loops don't have static head but do typically have more restrictive plumbing, especially on the intake which has the greatest effect.