Aw man... don't let it get you down. I just read that three page thread on Marine Depot that you linked, and got a quicker overview of your tank even though I've been following this thread for some time now. Keep in mind my tank is almost 5 years old. I've seen much prettier tanks that weren't as old as mine, and I'm sure there are very good reasons for that. Younger tanks go through all kinds of swings, and your tinkering can be a negative versus keeping your hands out of the tank.
1700g - wow. That's a lot of water.
Salt - If you are going to go that route and make your own, you do have the cost to consider of making RO/DI water. I think your Kati/Ani system won't work out so well for tap water unfortunately, but that is your call. The bad thing is the 4:1 ratio using an RO system. I've used Kent, Oceanic, Instant Ocean, and Red Sea Pro Reef. I'll never use IO again, and I had a bad nine months with Oceanic when it first came out. A few years ago, Kent had a bad batch that went out nationally, and many tanks took a huge hit. The salt lacked alkalinity in a big way. Kent sent me new buckets to replace the bad ones, but told me I could keep the old and just buffer up the alkalinity. I still have them to this day, clearly marked so if I do use them, I'll remember to add baked baking soda first. I was actually doing that with a couple of barrels I made up, because the pH was measuring so low - I didn't even know the problem extended to anyone else until a LFS in Arkansas called me up and asked about it, and linked me to a thread here on RC. The other salt I've been using for a few years is Red Sea Pro. I like it. It dissolves well, and the numbers are good.
No matter what brand of salt you use, each time you open a new bucket you need to measure the normal stuff to make sure it is a good batch. This is just a good practice to be in. With your system, every bucket would probably be used in its entirety, since you'll probably mix up 160 to 200g at a time. For my system, I make up 55g at a time, which means a bucket lasts about 3 water changes (or six months - LOL). I know I don't change water as fast as others, and now that I just bought that 250g reservoir, I might try changing more frequently to see if my reef suddenly surprises me. Not that it really has room for a growth spurt, but it would be nice to see some corals get bigger finally.
The concrete pads in your reef - I've seen it done before, and I don't know that it is a problem that you have to worry about now. Usually any concrete stuff that we make or use is soaked in fresh water for 6 weeks or so, to make sure the pH is stable (and end any spikes). That would be a good time to measure PO4 as well. Since you did this a year ago, it might be pointless but if you happen to still have one of those you could do a test just to get peace of mind. Whatever it might have had in the concrete before would have leached out by now, especially with you using PO4 removers as you have.
I didn't expect the Vodka discussion to go well over there - LOL - but you probably never hit that magic level where it makes the difference. Remember, it took my tank 7 months to hit the number where the nitrates dropped finally. At 11 months now, NO3 continues to measure 0, I'm happy to say. The birdsnest in my tank never looked this good.
The resistance to using Lanthanum chloride seems to not be unusual. I was surprise that the Dallas World Aquarium doesn't use it, for example. Eric's comments indicate that he's not on board with it either, at least for now. Dosing it in the display in an area of high flow is what I've done in the past, but I've also simply dripped it into the return section of my sump. Within a few minutes the entire system looks a bit cloudy. The only coral that doesn't like it are the Lavendar Frilly mushrooms, and a day later they seem back to normal. I also dose it late at night when the fish are at rest, as I do think it can't be good for their gills. Swimming through it actively versus just resting; I tend to hope that less activity means less respiration and hopefully avoid doing them any damage.
