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Rating: 2 votes, 5.00 average.

Coming from the freshwater world to a marine tank: the differences

Posted 03/15/2014 at 01:12 PM by Sk8r

Freshwater hobby to Saltwater hobby: the differences.
1. salt, obviously. The salinity level of a tank should not bounce around. Use of an ATO (autotopoff) is recommended.

2. ph becomes a fairly useless reading: track alkalinity instead. PH rises and falls during any single day. Alk is tightly locked to the calcium and magnesium in your tank. If one depletes, readings will start to fall. Keep the mg around 1200-1300, keep the calcium about 420, and the alk around 8.3-9.3 and your fish will be comfortable in their skins, their slime coats will be strong, disease will be rare and your corals will grow.

3. We don't encourage algae except in a planted fuge. A Fuge is a nice thing to have: little shrimpy things grow there to feed your fish (they sail right through the pump) and it oxygenates and improves your water. But if you can't have one, you'll be ok. Plants are also ok in a seahorse tank, but these slow-moving creatures have other requirements which make them not-so-easy-care and require a separate tank from your reef or fish-only.

4. sumps and live rock. It is possible to keep a 30 gallon saltwater on a Penguin filter, but it's harder. The bigger the tank the harder that gets. Advanced as waste-can-sized canisters have become, they still can't do one operation: break down nitrate and sop up ammonia the way adequate live rock can do. They stop at nitrate. And ammonia can result, and you have to clean your filter periodically---which keeps your tank on the ups and downs of nitrate. A no-filter tank with enough live rock doesn't do that. You never clean the filter because there isn't one. But your nitrate readings (if the tank is not overcrowded) are in the 5's, and you don't get spikes and valleys: it's smooth and same. Corals really need that. The suggestion is about 2 lbs of live rock per gallon of tank water. And it needs to be rubbly, holey rock (more surface). Yes, you can grow your own live rock: just put one live rock in with your cured base rock, and give it 8-12 weeks with no fish and the place will be crawling with life.

5. The presence of a skimmer --- a froth chamber: this is your surf. This removes amino acids and other things you'd like to be rid of. The bubbles decay in a dedicated chamber, turn to mucky green liquid, and you get to pour it off, a cocktail of things your tank can live better without.

6. You'll hear the term FOWLR, pronounced 'fowler'. It stands for a fish-only tank that relies on live rock---may not have a canister, but may have a sump, maybe a fuge. It will, because of the lack of corals and because the fish load is heavier than a reef would like, often produce more nitrate than you'd like in a reef---which is defined as a tank with coral: corals really don't like nitrate. Add a mushroom rock and your FOWLR is technically a reef. Corals are living filters: some are nearly bulletproof given any reasonable care...I've had stony coral actually survive a cycle with testable ammonia. The most common reason for keeping a FOWLR without coral is that the owner likes the bare-rock and fish look; or keeps fish that will eat coral. Some do. On the other hand, I've yet to meet a fish that really likes buttons and mushrooms or green star polyps, so you could probably manage either way.

7. because you don't have a lot of green plants, you have a struggle with hair algae and phosphate. There are reactors that uptake phosphate: a GFO reactor. Phosphate is bad for fish and corals. Good for plants.

8. Marine fish are sold as a step above hatchling! Watch this! That cute little fish may grow rapidly to be a foot long. This is why though 30 gallon tanks are commonly sold to salt water use---they're classed as a very small tank. A marine FOWLR may be 6' long and more. A lot more. On the other hand, there ARE marine fish sold as adults whose size you can rely on: blennies, gobies, some basslets. And they're small. Watch it on damsels. They're a 100-gallon-tank item: the only damsel that will live tolerably well in a 30 is a pair of the smallest clowns---also avoid tomato clowns and maroons, which are the larger clowns. In general, in a 30, is arrange a community without pairs of anything and of fishes that are sold as adults and that stay small.

9. we run a little hotter than a freshwater: about 78-80 is good. 85 is way too much. So oxygenation becomes a bit more of a problem. Be sure your surface gets good exposure: agitation of the surface is recommended; a hood fan array is not a bad idea, especially if all those submerged pumps (main pump, GFO, and skimmer) overheat your sump. You can run non-submerged pumps, but a sump makes everything Soooo much easier.

10. Lights. Lights are far more variable and define what you can keep. Stony coral and clams require highest light. Soft coral and fish require less: be sure you're sold the right kind of lighting from the start.

11. Sand; sand is not 'sand' in the silica sense: silica gives problems. Go for aragonite marine sand---and wash it! Washing 20 lbs of sand can take a 5 gallon bucket, a garden hose, and 30 minutes or more. The endless flow of milky water is amazing. Rinse til clean. If you buy 'live' sand---check the expiration date.

12. Given all the above, marine tanks, whether FOWLR or reef, are not as hard as you imagine. You need some tests (a refractometer to measure salt precisely; a test for alkalinity; a good thermometer. And a decent skimmer: go for one rated for 2x your tank volume. As a rule of thumb, a 55 gallon tank uses a 950 gallons-per-hour return pump. Flow-through rate is important.
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