Hi all,
I've got a setup that has a DT and two sumps (S1 and S2)
DT = 150gal
S1= 35 gal Ecotech miracle mud system, carbon, chemipure, polyfil (essentially chemical)
S2 -= Red Sea Reefer 525 XL 56Gal sump with 2000SRO Ext protein skimmer and bioballs (essentially mechanical). Also has Sea Lettuce, about a softball size where water from S1 enters S2. 2 filter socks, 100 and 200 microns.

I was going to put in a quarantine tank (30gal) but a lot of various issues made the placement of this particular tank not optimal. I'm still doing a QT but it will be entirely separate from the main loop.

Speaking of loop, my loop has 1 pump (Varios8 pushing to T split, half to DT and half to S2). I get about 750gal/hr flow rate through DT according to my FMM. That's after the split, so some more amount of gal/hr is going to S2. I've gate valved it so that about 70% goes to DT, and 30% goes to S2.

Then repeat... Feel free to correct me. Diagram: diagram.JPG


Scenario: I now have a free 30 gal tank. I've had a very difficult time keeping my refugium from spitting macro algae into the mix, which eventually finds it way to my return pump. I also want to have an easy place (not my DT) to dose things like cal, alk, mag, and to daily water changes.

So I'm thinking of doing this:
2nd loop using a siphon down from S2 to S3, then pumped back up using a DC-2500, which I can hook up to my Apex.

This second loop would not be attached to the first, and I'd failsafe it with float switches to my breakout box on my Apex.

Why would I do this:

Advantages:
1. I have 30 more gallons I can add to the total water volume, better stability
2. I can make this a dedicated refugium
3. Plumbed with union ball valves at each end, I could easily isolate it as a quarantine tank when needed, but use it for the health of the system all other times (assuming nothing gets sick while in QT)
4. Could be the place for WC and for dosing (again, until a fish gets sick or is QT, then it's isolated so maybe not)

Disadvantages:
1. two pumps, not connected but an extra failure point
2. Something will go wrong, and water will be everywhere.
3. I'll never figure out where to put my Tunze Osmolator to measure water level evaporation. Pretty sure it's still S1 above the return.
4. It's just more complicated. Maybe too much.

Thoughts? Any advantages to doing this?

The good news is this is in the basement, temp is fixed around 70 year round, cement floor, etc... Tank is at 78 degrees F, dKH is 10.5, Cal is 400, Mag is 1300, PH is 8. It's not heavily stocked tank... added these a week ago.
5 chromis
1 rabbit fish
1 diamond watchman
1 BTA
2 emerald crabs
1 skunk cleaner shrimp

Coming tomorrow:
Purple tang
2 bonded paired blood orange clownfish
Derasa Clam
3 coral frags
green metallic star polyp
Silver branch pumping Xenia
Grape Cristata

APEX RELATED QUESTION: Is there a way to have the Apex warn me if water levels between S1 and S3 get out of whack. So far they've been rock solid except for evaporation. I'm assuming I can add a few optical float switches and trigger something off of that. Ideally, it would be a soleniod gate valve on the siphon leading down from S2 to S3...thoughts?