Intermittent vs. Continuous skimmer use

[a1amap]

I have had my skimmer off for the last 3 weeks on my 75g. No Ph swings no nuisance algae or cyano. I did get some extra diatom on the sand but I increase the flow there. I used no other filtration method, no floss, no bags nothing. I did have a sponge on the return pump to keep the snails and shrimp from becoming sushi.. I was testing this becasue I don't want to run skimmerless on my new set up (210g) but wanted to run intermittent.
When I upgrade I will use my closed loop to create a gyre which will continue for 6 hours then shut off. A 2nd pump will start and reverse the gyre for 6 hours. 30 min before the 1st pump goes off the skimmer will come on and remain on for 2 hours total. This will reduce the electricity used by 1/3 and since the skimmer will be going on at timed intervals throughout the day, I highly doubt there will be Ph swings. The time when the gyres are in total chaos should stir up any waste and hold it in suspension till my oversized skimmer can get it.

 

[Icefire]

The idea behind a skimmer is to remove waste before they get converted by bacteria.

Running at half or 1/3 of the time is a waste of time if it remove "all" organic during that time on. Unless noise is an issue, just run it 24/24. You can't strip too much with a skimmer unless you get a 20-30x too potent one, like one for a 1000G on a 30g nano.. just the feed would do all the flow in the tank.

About the 40G frag setup with a 120g sized skimmer, I would run it 24/24 to have the best water possible. A skimmer take some time to build a head and skim good and cutting it short after 8h might just get a good skimming for 4-5hours only