Thanks for this! Installing my S 850 G2 on Saturday so this is super helpfulJust a quick write up on how to dial in the overflow of the aquarium.
1. Fill your tank to just over flowing into the sump. STOP putting water in the tank.
2. Fill your sump to the desired level. Do this with your return pumps OFF and Valve closed for the Tank.
A. Fill to about 3 inches from the top of the sump. This will overflow the sump baffles.
3. Now fill or remove water from the tank's weir box. Have the water level just about .5 to 1 inch below the main drain.
Now the fun begins or terror depends on you excitement level. If you have oversized your return pumps do NOT put them at 100% when you turn them on. Lots of noise and water my jet out of the tank. Speaking of that put your returns just below the water level of the tank.
Now I did it this way, you can do it the opposite, (which was recommended, but I found this easier. And a lot less nerve racking.)
4. Open your over flow valve FULLY OPEN. For Red Sea Tanks, that is a lot of turning to the left, if you have the stock valve.
A. Now mark the sump water level. This should be the line you NEVER go above filling your sump. Mark it MAX WATER LEVEL.
5. Turn on your return pumps, again if oversized DO NOT run at 100% yet that is if you want to later. Let the water level stabilize for sometime. It will be noisy.
At this point the tank weir box should be filling up with the water from the sump. Once the water level reaches the top of the return over flow water will be returning to the sump. LOUD and you might have to pee because of the running water noise.
6. At this time determine your flow rate by adjusting your pumping speed. I have mine set at 19% right now. And it seems that I have good flow in the tank.
7. Once your flow is dialed in, now start closing the valve from the over flow. I did full turns, and waited serval minutes between turns for the flow to stabilize. While you are doing this the you notice the flow and level of water rise in the weir box. Keep doing this slowly and your tank will become silent! Once the tank is silent STOP adjusting.
8. After the water level has stabilized mark this level on the sump. This will be the level if you are using an ATO (Auto Top Off) to fill your sump with RO water to replace the evaporated water from the tank. I marked it with painters tape and called it running level.
9. After you have done this and someone might ask is the filter system working?!?!
10. Power out Test! Turn everything off. Watch the water level in the sump rise. It should go to the first mark you put on your sump. After the water has stopped flowing to the sump. Turn everything back on your silenced tank. Have good night sleep now!
But another important point, when you change anything in your tank you will have to do this again. If you add a lot of fish, rocks or sand. You might have to remove water from the sump.
I really like the Velcro idea. I tried that too but some things are too heavy so I have to tone it down haha
