It was fresh water. The connector to the RODI exploded one night and I woke up to my daughter saying there was running water in the tank room. Believe me, that is not how you want to wake up. I'm not good in the mornings so imagine me, head full of cotton wool, eyes half open running down the stairs as I plainly hear a sound like someone has ploughed a pickaxe into my tank.
I opened the door and I was greeted by a small swimming pool. Have to say it is a testament to my good design - building the tank room right on top of the slab so the footers contain any water. But it shouldn't have built up like that, just the drain was blocked with crap. So there I was looking on, not wanting to jump into a foot of water with the Sequence and Hammerhead fully submerged. At that point I did not know where the water was coming from. I shoot a finger into the water and didn't die on the spot so I jumped. Water was spurting out the Sequence so I immediately thought seal leak. Turned off the ball valves and unplugged it. Then I saw water spurting out the Hammerhead. Closed valves turned it off. So if this water is coming out the pumps how much is left ion the tank I though. So I ran into my office to look at the tank. I saw no water line so there was either no water in it or it was full - and then I saw a fish swim out from behind a rock. Okay, so water wasn't coming from the tank. Dived back into the pool. And only then did I realise that there was a sound of gushing water (it was early and I was panicking

). So I followed my ear to the tap and saw the line that should have been connnected to the RODI was dangling by the side of the sink shooting water out full pelt.
So the water drained out but the umps never worked again. Not sure how long they were submerged. This was about 6am so could have started any time since about 2am. But the drain was pretty blocked and a tap open wide like that would have filled the room in under an hour I'm sure so I don't think they were submerged long.
Anyhow, I'll take them apart tomorrow and see what can be done. This was over a year ago though (I think).
Well, today I cleaned the Deltec 902 skimmer. Had it in vinegar for 24 hours. Also cleaned the Iwaki return pump in the vinegar. Clean up all done and suprisingly painless I hooked the skimmer back in and turned the Iwaki on. Waited patiently for the water to fill the overflows and trickle down to the skimmer. I knew I'd have to choke the Iwaki back (it was open wide at that point as I hadn't cleaned it - ever). So I'm watching the skimmer fill. And fill. And fill. And fi.....ck. Suddenly I had the Trevi Fountain with water spurting out the skimmer like a geyser. I .... am ... so .....dumb. Scrambling now, I turned off the return wondering what had I done to screw things up this time. Oh yes, I forgot to hook up the return to the sump and the ball valve was of course closed.
And as fate would have it my RODI line split yesterday. Meant to fix it today but didn't get around to it. Had to put in 20g of tap water which is bare minimum really (still needs another 20 but can wait till tomorrow with fixed RODI).
So yep, don't do anything for a year, get stuck in, and it's immediate drama.
But to be honest I enjoyed it. Been meaning to do it for a year. Even bought the vinegar a year ago and it's been sitting there waiting all this time. Having to hook up a little bypass drain was the thing that stopped me doing it but when I thought about it for 2 minutes the solution was simple and took 5 minutes to make out of bits of old discard pipework. So next time I won't dread it and I won't forget the return, heh. So chaps, progress is being made.
As soon as the wife signs off on it I'm going to order some LR from Okinawa and start redoing the rockwork.
Oh yea, please do chip in with some Tunze recommendations.