There are many beautiful ways to do saltwater tanks. We have almost all seen outstanding reef setups . What I am describing is a far lower cost and lower maintenance setup for aquarists that have access to the ocean locally and are interested in exploring their local marine ecosystems. My region is US mid Atlantic coast, but the same basic method should work for anyone with access to the ocean. It requires only the very basic equipment (prices are approximate):
Step 1: Materials:
10 gallon all glass aquarium - $15
Aquarium air pump for 10 gallon tank - $10 to $15
4 ½ inch diameter sponge filter - $8
Air tubing - $1/ft.
Top – commercial - $20, or sheet of glass – less or free
Light – commercial fluorescent hood - $30 to $50, or 4’ shop light fixture - $30
Miracle Gro Organic Choice potting mix, 16 qt. - $8 (optional, but I like it!)
Three five gallon buckets with covers - $5 each
Sand – usually free
Water – free if you have access to the ocean.
Flora and Fauna – free if you have access to the ocean.
Total – About $100. It should be possible to reduce this considerably if needed. Used aquarium equipment is often very inexpensive, especially at club auctions. Many people have buckets. I usually have scrap glass around to cut an aquarium cover. A hardware store can cut one for you if you do not cut glass, or do not have scrap. The light is the most expensive part of the setup, but it is critical to have enough light. I consider the cheap incandescent aquarium lights to be basically worthless. LEDs are becoming an alternative, but require DIY expertise in both LEDs and in aquarium lighting, or trust in the manufacturer and a pocket full of cash.
Many people have fluorescent lights such as shop lights or fluorescent under counter lights that they can appropriate for the cause. I use a lot of 4’ shop light fixtures, putting one over two aquariums, or putting houseplants under the other half. With two tubes, they deliver twice the light of a typical commercial fluorescent fixture for a ten gallon tank.
Step 2: Get Ready:
Rinse your aquarium well with a hose, and put in about an inch of the organic potting mix. This layer is optional. I used this option in the aquarium pictured in this instructable, and I like it. Cover this with an inch and a half to two inches of fine sand. You can buy silica sand, or silica free play sand (my preference if I can find it), or appropriate sand from the beach. Don’t go to an aquarium store and spend a bundle on sand. Put in the filter, and hook up the air pump to it. Have the cover and the light ready.
Step 3: Go to the Beach!
Do some collecting. Bring three 5 gallon buckets with covers to prevent splashing saltwater in your vehicle. Bring whatever equipment you feel comfortable with for collecting - mostly collecting seaweed this time. That might be snorkel gear, it might be old tennis shoes if you just want to get your feet wet, or it might be a long handled net if you don’t want to get wet at all. Look for green and red seaweed mostly. Sea lettuce, Ulva, a green one, is great. It is hard to kill and easy to grow. The bushy red sorts like Gracilaria and Agardhiella generally do well. I have found it best to avoid the brown seaweeds. They look great of the rocks at the shore, and they seem to quickly die in the aquarium. They can turn a good setup into a foul smelling mess quite quickly. I know that they can be grown, but I do not know how to do it. I usually get some reds and greens I have had before, and then an assortment of small bits of those I would like to try. Not much of any one kind of these. Some will grow. Some won’t. Small quantity is important so that those that die can decay without using up all the oxygen in the water and killing everything.
I usually mostly restrict myself to seaweed on this first collecting trip. I might pick up a few snails. Put your collected loot in one bucket of seawater, and fill two of your buckets with just seawater.
When you get home, spread newspaper over the sand in your aquarium, and pour in water to fill it up. Remove the newspaper, add your collected material, put on the aquarium cover and light, and turn on the air and light.
Let it be for a couple weeks. Make sure the filter is bubbling. Make sure it gets plenty of light – at least twelve hours a day. If something is obviously dead and decaying, take it out. The water should be clear and not smell bad. It may pick up a bit of tea color from the organic potting mix.
Step 4: Go Back to the Beach!
Now you aquarium should be ready for some animals. This time also bring your three buckets – two for getting seawater, and one for seawater and your collected critters. You may pick up some seaweed bits this time if you find something interesting, but this trip is more for fauna. Pay attention to regulations – some areas are off limits for collecting. A minnow seine is good for catching things, especially if you have a helper so one can take each end of it. I have caught a lot of stuff alone with a little seine though, pushing it ahead of me in the water. Seines catch an interesting assortment of little critters. Little fish, little crabs, maybe even a bay scallop. I find little grass shrimp to be among the most entertaining to watch. A butterfly net serves as a dipnet if you treat it gently. I have spent a lot of time wading around with one of these. I like to check out grassy patches, weedy patches, and rocky shores. These places have more life than a typical sandy beach. Some creatures you may encounter need special care. An urchin is good fun, but it will eat all of your seaweed and want more.
Asteria, the common sea star on the mid and northern Atlantic shore will quickly die without the right food. It does well with a good supply of very small blue mussels and small mud snails. Collect sparingly. A couple dozen little grass shrimp and a dozen small mud snails is plenty for a ten gallon tank. A half dozen inch long fish is enough for a different tank. Putting all of these together in the same tank is too much.
Step 5: Watch and Expect Change!
Now you have a setup that will grow, change, and almost certainly surprise you over the next several months. I always find critters that I didn’t intentionally collect making an appearance. It seems there is usually a tiny crab that will eat and molt, becoming a bigger crab each time it molts. There is always a mystery animal that makes an appearance. The mud snail shells may become covered with feathery hydrozoans. Marine worms may colonize the substrate. A seaweed you didn’t remember collecting may pop up and grow. Shrimp may develop eggs. Snails may lay eggs. Probably conditions will not be right for most reproduction to succeed, but you never know.
Step 6: Do a Little Maintenance
This isn’t a huge chore. Replace water that evaporates. The salt won’t evaporate, so use fresh water. A dechlorinator solution from an aquarium store makes tap water safe. Letting tap water sit uncovered for two weeks does the same. Change about half the water every couple of months. Scoop or siphon it out, and replace it with collected or artificial seawater. If artificial, you will need a hydrometer to get the salinity in the right ballpark. Do a little weeding if the seaweed gets too overgrown for your liking.
Step 7: Learn
It’s fun to figure out what you have! There are good field guides available for many localities. The internet has species lists for many areas, and descriptions of many species.