Thanks for your thoughts...
I would LOVE some specific suggestions on SETUP.
I had two fish and never added more than 3 more at a time.....the most I ever had (55 gallon) was 5 fish.
Wet/dry?...what is that?
I can pull the Holey Rock...just thought it looked cool and others use it successfully.
55 gallon tank----with canister and 2 thrusters to aggitate (but is that enough?)
I'm VERY OPEN you suggestions: Sounds like I need a substrate filter at the very least to start.
5 fish in a 55 gallon is not too many as long as your biological filter is adequate. The rock in your tank and the bioballs in your canister filter are meant to grow benefical bacteria that turn the fish waste into less toxic chemicals. It is called the nitrogen cycle. Are you familiar with this? In saltwater tanks, if you use porous rock in the tank, it will grow this bacteria and help with the cycling. This is called "live rock". As a general rule, it is recommended to have about 1-1.5 lbs. of live rock per gallon of tank water if this is going to be your main means of biological filtration. Now, some decide to not use live rock and instead aquascape with stuff that does not grow benefical bacteria because it is not porous - example would be artificial coral "drop ins"- To compensate for this, the filter is a sump with large amounts of the bioballs. (look up wet-dry filtration).
Texas holey rock is very popular in African cichlid tanks because it is limestone. It slowly leaches out chemicals that work as a buffer to keep PH in a high range of 8.4 -to 9.0. That is of course too high in a saltwater tank. That being said, I don't think one piece of holey rock could throw off your PH that much, but I just don't know for sure.
I also cannot be sure if your two thrusters (powerheads) and the canister filter were adequate for producing dissolved O2. You can test for the amount of dissolved O2, but I don't know that I would go through all that trouble right now. But, I do know that it is an issue with saltwater set-ups and thus why it is recommended to utilize a wet-dry filtration set-up, use mesh screen vs. glass lids over the tank, and to have significantly more flow and surface agitation in the tank that what you would have in a similar freshwater set-up.
The fact that you were able to keep a couple fish successfully, and then had problems once you added more makes me think it had something to do with the amount of biological filtration (which could cause an ammonia spike), or the level of dissolved O2. It sounded like you lost the fish quickly? Typcially, if they develop ich or something, it is a slower process and not like you wake up one morning and find them belly-up. You would have started to notice the fish acting weird, seeing white spots on them, stopped eating, etc. before you lost them.
RODI stands for reverse osmosis deionization filtration for water. Again, the fact you were able to keep some fish successfully, your water could not have been too far off, especially if your LFS said your water parameters were spot on. However, it is highly recommended to use Reverse Osmosis water to mix your saltwater and if you are doing a reef tank, RODI water is recommended.
You obviously care a lot about keeping fish and want to make it work or else you wouldn't be on here. Do some research, know what everyone is talking about when they sayRODI, wet-dry, live rock, etc. Get your own test kit and check these parameters for yourself. If that were my tank, I would put in an e-shopps wet dry sump, and change the aquascape to about 40-50 lbs of dry live rock. Let it cycle for 4-6 weeks, and then slowly add hardy fish up to 5 total. I would use RO water, and use a spectrometer to check the salinity when mixing my saltwater. Keep the thrusters going and make sure I used a pump that will cycle 55 gallons 3-5x per hour. I would also invest in a reliable and inexpensive thermometer.
That IMO would make for a good FOWLR set-up or fish only with live rock set-up. You can also do a search on you-tube or here on FOWLR or fish-only set-ups. The possibilities are endless. When you describe your set-up, it reminded me a lot of set-up you would use for an African cichlid tank, so that maybe part of the problem. Good luck!
