Estimate flow loss when reducing pipe diameter?

[kilnakorr]

Yes the flow in the reactor and UV filter would decrease dependant on the fittings and their would be an increase in the total flow dependant on the size of the fittings used. I oversized my fittings to has the least amount of increase in resistance so less drop in output.

Fittings are pretty much fixed, so can only change a few. I have roughly 40 cm pipe also, that cannot be changed unless I remove soil from the tank.

The best rough estimate to get, give it a try, take 1-litre cup and a stopwatch... 🙂

True, but really don't want to mess with all the plumbing

It seems that it has picked up the flow. Guess it just needed to vent a bit.
PH has dropped nicely without a gas build up in the reactor

Going to try a diy spraybar and see if I like the flow and don't mind the look. Guess the filter will tell me if flow decreases. Guess that's a plus😉

 

[zozo]

True, but really don't want to mess with all the plumbing

The issue with formula is next to a load of others you need to know the Pump Pressure. Yet not seen aquarium filters/pumps specify this...

But if you like to have a go at it.
https://en.wikipedia.org/wiki/Hazen–Williams_equation

Some pump suppliers have online calculators based upon Hazen Williams Model.
Yet i didn't find any in English... But a guess is it must be out there somewhere. I wouldn't know the proper English search query for you to find it. Pipe line capacity calculator? Maybe..

 

[kilnakorr]

The issue with formula is next to a load of others you need to know the Pump Pressure. Yet not seen aquarium filters/pumps specify this...

Very true.

I actually think, I just need to calm down.
I don't have any major issues, just want a slower but more even flow at one end of the tank, but at the moment everything is actually doing fine in the tank, so think I should relax and enjoy for a while🙂