put a fan on the basement tank on a timer(to coincide with your lights).....this will drop the tank probably three degrees.....personally I wouldnt waste money on a chiller....if your thinking about going that route then consider a portable AC unit for that room, then both you and the tank are comfortable:wink:

wow, what type of corals do you keep at 84 and 86? because many sensitive acroporas and SPS would surely RTN at this high temperature, especially the deep water.

Yeah, I do have some further options to keep my tank temp down. We actually have central AC, so the room temp isn't a problem. But I do have canopies and covers on my tanks, so that is really what keeps them on the warm side. I can open the door on the canopy and remove the tank cover. I am sure those will help.

My real question, though, had to do with the effect of higher phosphates on SPS that are used to zero in my main tank, and also how high heat my fish and corals can handle in my downstairs tank.

I am still hoping my phosphates will continue to fall in my downstairs tank with the GFO, and would like to hold off having to combine the tanks as long as possible. I know once summer hits, I will need the chiller for the downstairs tank too, as I don't want to make the temporary aids (like canopy open and tank cover off) permanent.

My 150 went from 80 to 89/90 daily for about two months during a summer when my chiller died. The fish all did fine and on the hottest day (91), I lost all of one species (5 different pieces of it throughout the tank), but nothing else. I probably lost some of my lifespan stressing about it, but the tank did fine. I wouldn't recommend it, but going to 84 shouldn't hurt much, unless you have a huge fish load. Then O2 might come into it. But if you've got good surface movement and a good skimmer, O2 should stay in the safe range.

As for PO4, I would expect a sudden shift in levels (either direction) might not be really good.

Wow, am surprised at how high temps the corals and fish can handle. My downstairs tank has only LPS and softies, no SPS, so am less concerned about the corals.

But because my SPS has been doing so well in my main upstairs tank, that's where my biggest concern is, if the P04 jumps up when I combine the tanks.

Thanks everyone for the feedback. I will take it day by day, and see what happens.

Just a note, when I say they were fine, they were fine and brown. So not REALLY fine, but not dead, and they did grow quite a bit :)

Understood..., but like I said, my downstairs tank has only LPS and softies, The upstairs tank has the SPS and is kept constant at around 78. It could not survive without a chiller, I'm quite sure...

Other than the summer, my downstairs tank is fine without a chiller, as that is in the basement floor, and the room temps down there are usually 70 or less. But on the main floor, where we have the thermostat, I have the AC kick in at 75. We have a northwest exposure there, so doesn't take a lot to get up that high when it is sunny out.

What happens, though, when the central AC runs, is the downstairs actually heats up, as the air circulates throughout the house. So the room temps down there are at least 5 F degrees higher than winter or spring. I know, sounds like of weird, but that is what happens....

Reallistically, to do this properly, you would want to run both products on both tanks, so that they are fairly in sync as far as perameters are concerned when you combine the systems. I think that from 0 to around 1.0 is a pretty large difference when phosphates are concerned. I would try to get the parameters more on the same level.

Are you able to put GFO and BioPellets on both tanks to start before you combine them?

Salinity is huge too. I combined two tanks once, not knowing that my salinity was waaaay off in one of the tanks (thanks to a plastic hydrometer) and the tank with the lower salinity's inhabitants all died. (mind you, this was just combining inhabitants into one tank, not sharing system water like you are, but still the same idea).

I agree, and ideally want to get all parameters the same before combining the tanks. Salinity is very close to the same, though, as when I do water changes, I only put new SW in the main floor tank, and the downstairs tank gets the old water from that tank. Saves on salt costs....:mrgreen:

And by moving my GFO over to the downstairs tank sump, I have brought the P04 down to .62 when I last checked a few days ago. I also just changed out the GFO, so will check again in a couple days, and hopefully it will be down more. The good news is that the main floor tank (with the SPS) still has zero phosphates with just the bio pellet reactor running.

This is the tank that went up to 86 a few years ago
http://img.photobucket.com/albums/v2...may0110004.jpg

The tank I have now has a mix of sps, lps and softies