Relation between NO3 & Flow/Flow Direction
 

My NO3 use to be really high and now that i have been using the Zeovit system for a few months
is lower.. @25mg/L (Elos test kit)
nothing seems to be stressing (except Plate Coral) SPS has decent growth & color..
however 25mg/L still is not desireble I want it much lower..
so now im questioning my flow or direction of the flow in the tank is not good enough for NO3 to be efficiently rid of by my sump/zeovit reactor
Can anybody offer some advice ??

Anybody ?
:neutral:

More flow and flow that is random/surging in your tank will keep waste in suspension longer and allow it time to go down your overflow where your skimmer and other filtration can take care of it. As for how much is enough... That all depends on your tank. What works for me may not work for you.

More flow is always better for SPS but make sure to get propeller type flow Not the impeller type. The cheapest way is to modify MJ1200's with the propellers (draw back is that they run backward sometimes and some time s stutter and make noise) or go with koralia or Tunze.

MJ1200 kit
SPS do like a lot of gentle flow so if you just put a power head close to it you will blow polyps away.
Look at the real reef ... Waves are crashing , tides in and out, billions of gallons per hour, we will never even come close to the real reef flow rates.

Having said all this perhaps flow is important, however what we should pay attention to is water quality, High ORP is very important as well as low Po4, No3 and the rest of the things that we are fighting continuously.
So in addition to flow keep your oxygen levels high, good water parameters (calcium magnesium, PH, KH) and your SPS will grow and show color. Providing your lighting is at appropriate level as well.

The point is as you already know that flow is only one of the parameters to watch for when keeping SPS.
hth