New to Saltwater starting with a 750 Gallon Tank any advice would be great!

Mareshow · Mar 28, 2020

Hello all,

I'll start this by saying I'm not new to the aquarium hobby, I bred discus and kept Arowana and stingrays for a while. I got out of the hobby for a bit because of life changes but am now ready to get back into it. I originally was going to do a freshwater stingray and arowana tank (love them!) but now that I have small kids and a family I think a reef tank would be more fun for everyone.

Originally I was going to go with a pressurized system for freshwater for filtration but now with the salt tank, so far I've been told don't do it. So instead I'm probably going to go with a sump, protein skimmer and refugeum. Now rumour has it you can limit water changes (which would be desirable) and for corals do some auto dosing. I'm a huge proponent of the set up right the first time and you'll never regret it.

Tank design is going to be three large formations near the rear of the tank with a "lagoon" set up for more expensive corals down the road. In front I'm going to place some smaller islands to place corals that like to take over. Tank size is 10'x4'x2.5'

So here's some questions, given that the tank is on the larger side I'm curious if standard tank rules still apply, or if I have to err more on the side of caution or be more lax. I plan on doing a reef tank with with cheaper corals and reef safe fish, then dive into some more complex fish and corals. I plan on designing the layout of the tank so that when the suspect coral nippers are larger, they won't be able to nip at the more expensive corals. All of this is of course way down the road.

Now the Questions:

How much live rock? I plan on using dry rock because I don't want to risk anything in this tank. But should I follow the 1# per gallon rule still?

Sump/filtration set up ideas to limit maintenance and encourage balance?

lighting suggestions?

any over all advice?

thanks for your input and looking forward to reading about everyones experiences, dos and donts

PatW · Mar 28, 2020

How much rock? Well, like everything, it depends.......
Are you going for a light, medium or heavy fish load. The more load, the more rock needed. You can always put rock in the sump if you need to supplement.
Also, no all rock is created equal. What is important is the surface area. A really porous rock might have several times the sites for bacteria as a relatively solid rock.
Then there are aquascaping issues. Some people like minimalist designs, others want lots of rock. Remember, if you get corals going they will add substantially to the structure.
By the way, I believe the pound per gallon is way over the top. I think I have about two thirds pound per gallon and I have quite a bit.

On filtration, there are all sorts of ideas. I like filter socks because they cut down on particulates. But they really should be swapped out every 3 to 4 days to work for nutrient transport. I clean mine with a hose. But for a 700, you would have to use a washing machine to keep it from being excessive.

I like skimmers. Pretty simple, good export, low maintenance. They are almost always over rated as to the size of tank they can handle. I have a 500 gallon super reef octopus on my 300 gallon tank with a pretty light fish load and it works fine. For a 700, you should look at a skimmer rated for at least 1000 gallons.

I run chaeto algae in a refugium to remove phosphates and nitrates. I dose both phosphates and nitrates. But having a honking big export balanced by dosing gives me considerable control. Chaeto requires a powerful refugium light and I have found that I have to dose iron (but not much) to keep it alive.

My sump is under the tank. But access under the tank is a bit cramped. I would rather have it someplace else where I had better access.

I would suggest planning on reactors. The water will get tinted an amber color. Running water through a reactor filled with activated charcoal will polish it.

You will also want to probably set up dosers to add 2 part if you get SPS corals going.

Getting a controller is nice. They can automate quite a few things.

You will want an RODI system and mixing containers for salt water and a reservoir for RODI water. Plus you will want an RODI water reservoir for your auto top off. With your size of tank, think of automating your water changes. Also for a 700 gallon, a 100 gallon water change routinely will work. But there are times when bigger changes are really nice. Being able to do 200 gallons would be a good thing. I would plan on being able to do water changes. Water changes are brute for e and simple. They can solve a multitude of problems.

For lights, I like LED lights. I have aqua illumination lights and they do a good job and grow acropora corals fine. But the eco tech lights give a more even spread and better spectrum. So they are worth the premium. But there are well regarded budget lights that will get the job done fine.

For fish, I am a fan of reef safe, easy and peaceful fish. I have a pretty light load but there is plenty going on in the tank. For fish, as you probably know, getting them to eat is the big deal. I have a tamarin wrasse, which is considered difficult. I got it because a trusted LFS said this fish was fine. It eats everything I toss into the tank. It is active, colorful, peaceful and no one bothers it. So go figure.

Matt Carden · Mar 28, 2020

Just to answer the rock question. If I were building a 750 gallon Display Tank, I would have a 300-500 gallon sump loaded with rock. Then you could Aquascape your DT any way you like without worrying about
# per gallon.

Skynyrd Fish · Mar 28, 2020

Super sweet! Welcome to R2R! This is going to be awesome. I would design your rock structures and not worry about a rock to gallon rule. You could get some rock and start dry stacking some structures to see what you like and estimate your final rock order. Start a build thread so we can follow this..

User1 · Mar 28, 2020

With a tank of this size you are going to need larger things like return pumps, power heads or other forms of flow control, closed loops, and of course a lot more of stuff to sustain it. Think salt, water storage, and other form of supplies. With more also comes more time in going from water ready to coral ready. Coral and fish ready does not mean go after the cycle is complete. You probably already know this.

In any case one thing I'd consider is ditch the dry rock and go with live. A couple choices with live with the best being TBS. It is by far the best source of rock with little to no die off from ocean to your tank. Meaning it is collected, packaged up fully submerged, then shipped airfreight over night, for you to pick up at the terminal. No die off. There are a couple other good choices like KP Aquatics who also collect from ocean but ship a bit differently and to your door. The main difference is that it isn't fully submerged so a mini cycle is a possibility.

Now having said this the cost is going to be a lot more. I'm not going to lie. However, looking at your tank specs your budget is going to be bigger anyway. I don't see a way around it. And why go with live rock? Well, dry rock is going to take a long time to mature. And by mature I the biological filter spreading through every nook and cranny there is. Complete surface such that you see the various post cycle stages and the facing rock work starting to darken with corrillian algae but if you take that rock, lift it, turn it, and the back size is moon rock bare because it hasn't matured. Having just upgraded to a 210 gallon tank using 150 LBS of dry Pukani rock I would say it is only now, 2 years later, matured.

Now there is one think you could do if you really want to use dry rock and that is cycle it in parallel of your tank preparation. Source the rock you want, buy some rubbermaid 100 to 150 gallon stock tanks, and cycle them in there. They wouldn't need any light or skimmer to start. Just mix water to proper saltwater specs, add rock, power head for movement, and let it age like a bottle of wine. GO through the cycle process testing water and changing as necessary. Months go by, tank is built, delivered, staged, then work through plumbing. Year later your rock is better and further along than starting back with bare rock.

Also one thing with a tank that size. Semi or custom is probably best bet. That is a lot of water should something fail. We are talking lower and upper bracing at a minimum. Overflow is also going to be important. I am biased towards full length coast to coast overflows with a smooth weir for maximum surface skimming but not everyone likes that. Can be internal or external. Again with a tank that size I'd ditch any additional power heads and cords in the tank and strongly consider a closed loop and a beefy and reliable return pump. Your rocks and aquascape could more than cover any plumbing and it would make your maintenance a lot easier. Then use returns with 1" sea swirls and call it a day.

Lots of options. Just figured I'd throw out the live rock vs. dry. I've used live rock from Fiji back when we could use it in 1999 / 2000. Best stuff I've ever used. Recent upgrade I used the Pukani and it was the biggest mistake I believe I ever made in this hobby. Cheaper yes. Long term potential? Great. Initial use for a upgrade bad...

Best of luck.

The guppy guru · Mar 28, 2020

I can try to give you some advise on live stock. You would naturally want some colorful or unique fish that are reef safe. ( if you want a reef tank). Mollies are an awesome fish you can get about 10, that is a good number they are small and will help you with the early stages of the tank once the cycle has finished. Guppies are also a wonderful fish for a new tank. If you need any info on the fish I just suggested go to my thread called want to know a little brackish secrete.

Auquanut · Mar 28, 2020

Welcome to R2R and to the salty side of life! You have lots of great questions. For best results, I suggest you break them down individually. Go slow, and research, research, research. The best advice I can give right now is to second the suggestion of starting a build thread. It's a great way of tracking the evolution of your tank and helps keep a timeline. You'll also get advice, encouragement, and tips/tricks from some very knowledgeable reefers. Best of all, you get a nifty "Build Thread Contributor" badge for your profile.
Glad to have you with us.

sp1187 · Mar 28, 2020

welcome to the show.
750g first time = hero status.

how much rock? what others have stated or none.
see my build thread as an example.

ScottB · Mar 28, 2020

Keeping a tank is all about maintaining a stable environment for our livestock. Maintenance is unavoidable, and at the scale you want, this is not kids play. The planning phase should start with the thinking: How can I make maintenance easy, so it always gets done?

From the spot you intend to place the tank, can you run some water lines (big and small) either through the floor to a basement area or to another room that can house your +250G sump, mixing station, sink, working table, 4 X 20amp separate circuits to run a bunch of chunky pieces of equipment, etc? Please say "Yes, of course!"

While there are reefing methods that significantly reduce the need for WCs, I don't know that I would recommend them to anyone "new to saltwater". A well equipped "fish room" allows you to build in a super fast and easy water change process -- or even an automatic water change process -- until you are comfortable switching over to a more "advanced" chemical mgmt method.

There is a lot of experience in this community and plenty of people willing to share knowledge. Although I must say at your proposed scale, the level of actual, personal experience thins out a bit. I'll just be in the stands, cheering you on.

And @Auquanut is spot on about starting a build thread that we can all follow along. I can't wait to watch you fire up that skimmer that is bigger than your oldest child!

Welcome to R2R!

Mareshow · Mar 28, 2020

Wow thanks guys for the Info! I'll be sure to start a build thread so I can keep a record of some of my poor decisions haha

So to give a bit more deal of where this tank is going. All the water lines, drainage and power is already ran. The tank is along my garage wall and I have dedicated a 18' space on the wall in the garage for all the components necessary for back up for this tank. The advantage is I have a sump rack ready for the sump that will allow me to work on the system and not have to crawl under the tank. The tank is already drilled for two 1.5" supply and returns on each end over flow.

for pumps I plan on using two exterior or submerged pumps (one for each over flow) with velocity booster to better increase flow in the tank. I'll post some pics and some more details in the build thread. now to find more live rock and sand... I bought out my lfs this morning...

I understand that more than freshwater, stocking timing matters (ie which fish you put in first, and which ones last) But we're a long way from that. Hopefully if all goes right I'd like to have it all set up and start cycling in two weeks