Have you tested the powerfail with your skimmer running? The skimmer will hold some water that will dump back into the sump as well. As will any reactors that you might run (carbon, gfo, etc).

While that does appear to be working well in terms of flood resistance, I myself would lose sleep over trusting that those return nozzles stay at that level forever and always. Here's what Murphy could possibly do to you one day...

You are in the tank and decide to move the nozzles away temporarily so you point them down while you are working in the tank. Or maybe you bumped them down by accident. Or maybe I guest was playing around and moved your nozzle. You are done working in the tank and forget to return the nozzles back to their upright position. Power fails while you are away from the tank. FLOOD.

I suspect you will be keeping a close eye on those nozzles for a while but if they get moved while you are not home that could be disaster waiting to happen. Or you may be tired one day and forget to check on the tank to make sure those nozzles have not moved either by accident or on purpose.

At any rate, I would lose sleep over those nozzles :-) With a check valve you would give yourself a larger margin for error here and since you already have the check valve, why not install it?

Or if you really want peace of mind without the check valves, install all your equipment, point the nozzles down all the way (this being the position that they could accidentally be placed in even if you don't intend for them to run this way during normal operations) and do a power fail to see if your sump holds the water. If not, drop the level of your refugium enough so that your sump does hold all the water in the event of a power fail.

Just my two cents :-)

Thanks for the heads up :) I am getting ready to get the skimmer in and test how things are. I will also try the power failure with nozzle pointed down too. Things are not going very smoothly like I wanted it to be :(

Part of the fun are the challenges that we face and overcome :-)

Look at it this way, it's better to find a problem now when there is no livestock in the tank and you are at home to immediately identify and resolve any found problems, rather than have the problem spontaneously occur later down the road when you are not home and you have a tank full of inhabitants. So ya, it's a bit of a pain now and I know you're just itching to fire it all up, get that rock in there, start adding livestock, etc, but if there is something that you can feasibly do to mitigate Murphy's influences you should invest the time (and possibly money) up front to do them.

I guess :)

Tuning the overflow is killing me!

There could be worse things to be worrying about though (and you will eventually worry about those too -LOL0, trust me :-)

With regards to the herbie, do you have your ATO yet? Are you testing the herbie with the skimmer running? Those things will affect your herbie as well so trying to get it perfect right now might simply be a fun time killing exercise at the moment :-) Honestly I would not worry about getting it just right. That can come later. Instead, dial it so that the water level is low and near the main drain or high and near the emergency drain. You'll get some gurgle but who cares right now. You're not done with all the other stuff that needs to go into the sump (ATO, skimmer, refugium media, filter socks, etc). All that stuff can affect your herbie and it is when all that stuff is installed that you should really worry about trying to dial it in just right. Or you can keep playing with it and frustrating yourself ad nauseam :-)

Tested the sump capacity with skimmer and the nozzles dipped to the same level as the return hole. There's just too much water (possibly around 10+ gallons) till the water level goes below the return line so my sump cannot hold the water :(

This is the 2nd sump I got. For some reason; I am having really bad luck with this thing too :twised:

Keep the sump and get a check valve :-) .. oh wait, there's one sitting on your table over there ----> :wink:

Or re-do the sump. Up to you :-)

I was browsing through some threads in reefcentral and people seem to literally "hate" it like putting a tang in 2gallon overly crowed mixed reef tank with little to no maintenance!!

Yes, I would be one of those people LOL.. BUT, I also know that a lot of people are using them with great success. The key is to have them easily removable with unions on either side so you can take them up and dunk them in vinegar on a regular basis to keep crud from building up inside. To me that's not an ideal solution but it's workable and people are working their systems that way today. If it were me I would just redo the sump since it's not currently being used yet.

And again, look on the bright side. It's good that you discovered this now so you can address it now rather than a few months down the road on a day where you had some people over and moved the nozzles around for show-and-tell and completely forgot to move them back to their up position. Murphy would have laughed at you and cut the power to your house on that day probably. He's a bastard like that..