OK. You want a reef tank with more community type fish it looks like. Clowns, anemonies, starfish, etc.
Starting with the mechanics. EVeryone please correct me if I am wrong, I am still pretty new to salt as well.
A saltwater tank requires more water turnover rate than freshwater. Freshwater requires about 5-10gph of turnover rate per gallon of water, so a 10 gallon tank needs about a 75gph filter or larger..I go with larger, I shoot for 10gph on my FW
Saltwater tanks require closer to 30gph of turnover, at least on the smaller tanks they do. (I have 175gph flow on my 5 gallon tank) For a tank that size, 135 gallons, I would suggest at least 3,000gph of flow through powerheads and the filter if you run one.
Filter--required? not required?--some people use them, some dont. Filters are not normally used for biological filtration in a FOWLR
(fish only with live rock) or a reed tank, since the live rock will provide all the needed biological filtration, that is the change from ammonia (i.e. fish waste, food buildup, etc.) to nitrite to the much safer nitrates. I use a filter simply for mechanical filtration, the removal of particulate matter, which without it would eventually settle to the bottom of the tank and deteriorate, this does have the theoretical benefit of creating a more active liverock since it would be required to do more biological filtration...I choose not to test this idea...
So on filtration, up to you. if you go without, then you need to make up the water flow you will lose elsewhere, with powerheads.
Biological filtration. Live rock and livesand perform this job for you. recommneded weights are 1lb sand per gallon, and 1-2 lbs live rock per gallon. I go close tothe 2lbs per gallon on rock. If you slowly stock your tank when you start getting fish/corals etc. Then to save money, get about 1/3 of it as base rock, which as mentioned, is not live, but will become that way over time, and 2/3s live rock, which will populate the baserock over time, namely as you increase the bio-load on the tank.
Sand-- There are typically two types. Sand, and crushed coral. Argonite is the recommended type, and most people recommend sand, since it is easier to clean, is more firendly to types of shrimp, starfish, certain fish, and snails...it is easier for them to bury themselves in and dig through, not as rought and abrasive, and smaller particles....also, sand has less of a chance for dead spots i nteh substrate, causing deadly ammonia,nitrites, and nitrates to build up. (nitrate is alot more deadly in salt than in fresh, in fresh, you can let it climb upwards of 30ppm and not harm fish, in salt, we try to keep nitrates at or very close to 0, most corals will not tolerate nitrates.) So recommended, Argonite sand. Argonite is very calcium based I believe, and will keep the pH high, in the 8.0 range.
Heaters, recommended is 5 watts per gallon, I dont know about large tanks such as yours (ok some people say a 135 is small..but to my living conditions, my 75 tank is huge...) I dont se how 5 watts per gallon can be feasible for over 100 gallons...but if that is still the nubers, then go with that much, and an extra heater. Always be redundant on heating systems. No sense losing hundreds of dollars of livestock when aheater fails and temps drop one winter night. I would recommend 3 heaters, and recommended temp is about 78*F
Get a thermostat, or two, for my 75g, I have three, two are in oppoisite corners, one I have stuck to the glass and I can move it around to check differant areas of the tank (again, saltwater tanks havea lot more flow, so chances of dead spots are less likely and tank temp should be even througout)
Hydrometer- is used to check the specific gravity of a water source. As salt is added to water, the density of water increases. A hydrometer is basicallya weight that is balanced normally to a SG
of 1.022 (that is 1.022 times the weight of straight water) at 78*F, since that is also the recommended temp. Hydrometers are inherintely inaccurate, and can sometimes be off alot, and the wter temp changes the readings alot. A refractometer is diffferant instead. It measures the amount that a bar of light is refracted by water...the refraction changes the more salt is in it, and gives a reading to the lvl of salt in the tank. Recommended salinity is typically accepted to be 1.022 SG
at 78*F for full marine conditions, I do know people who run their tanks as high as 1.025 on large reefs.
This brings us to the salt. You will use Marine Salt to up the salinity in your tank, most common I think is Instant Ocean Sea Salt, the bag has a pic of a couple of ocelleris clowns on the front. you will need just over 2.5 15lb bags jsut to get 125 gallons to 1.022 SG
Lighting--This I cannot help out much with. But for a high end reef tank, you will need LOTS of lighting. There are many types of light, and colors, and for a proper tank, you will need to have lights in many of the differant spectrums. The two most common lights are your whites and actinics. The white lights recommened is a 10K color, which is an aweful bright white light..almost blinding to look at. ACtinic is that bluish lookin light over saltwater tanks. To give you an idea, There are people on this board that use 96 watts of power compact lighting over their 10 gallon tanks. Now while I doubt you will need 1,000 watts of PC
lighting, you will certianly need a few hundred if you want to be able to keep every type of coral, and up to apoint, more lighitng normally means bettre coloration as well. Lights heat up a tank alot, so many people run small computer fans across the surface of the tank water to cool the tank down. I cannot keep my 5 gallon under 80*F just because my 25watt light over it heats it up that much, but my 10 gallon with 50 watts is easier to keep cool due to the amount of area under the hood of the tank.
Refugiums, sumps, etc. OK, in freshwater, sumps are used on large tanks to increase the amount of biological filtration without needing a crap load of large HOB
filters...which is what I do BTW...while still getting alot of flow. But as we have discussed, you dont need a filter system for biological filtration. There are two other reasons I know of that people use them, and they are kinda related. One, all the heaters that will be needed, look like crap in the tank unless hid very well, so they are placed in a sump tank to hide them, while still heating the tank. The other reason is that 2 lbs of live rock per gallon can take up alot of a tank. If you where to set up a large sump, you could possibly dump say 1/3 of your live rock in it, especially the uglier peices
and free up some viewing area in the display tank while still getting the same amount of biological filtration out of it. A small third reason, which I feel is more pertinent to smaller tank, is the addition of more water volume, which helps to stabilize wtaer conditions. Yet another small reason, is that when I do water changes on my 75 gallon, I have to turn off my heaters and filters becuase I am dropping the water lvl of the tank, and then I have to pour water directly into the tank again. With asump, while you are removing water directly out of the display tank, the water lvl stays the same, so conditions in the tank do not change, and you can add water back in the sump, and not have to disturb your main tank....yet ANOTHER reason...As time goes on between wtaer changes on my tanks, the water lvl drops in the tank, which looks unsightly, and can actually decrease the efficiency of my HoB
filters. With a sump, the water lvl in the main tank does not change even while water evaporates out of it, the water lvl in the sump drops though, but it is easier to top that off as well.
Conclusion on the sump. They are great, they help out, and certainly help with making your main tank look tons better., but require more room (which I dont have) more money, and more planning. If I had the room though, I would do it with my tanks...all of em.
Now this is truuelly just a very BRIEF introduction to saltwater tanks. You will need massive discussions over stocking for fish, how to take care of corals, and what will work with your fish. Discussions about what type of cleaning crew to get, how many etc...what to do when you get a bad hitchiker on live rock, how to keep the tank up and running, and the fish in good health. What their diets etc should be, and many many many more things.
I am not tryin to scare you away from Saltwater, even though they can be alot of work in the beggining, the end product is well worth it, I dont even have fish in my 5 gallon and I love the way it looks already..which is why I am upgrding later this week...to get more options for stuff to do.