Old Wives’ Tails

These are things you will encounter during your time in the saltwater hobby I’ve found to be half-right, misleading or just plain wrong. Read on and you will see what I mean.

The idea you have to pump water in and out of your tank at 10 times the volume of your tank isn’t necessary. I have been waiting for years for someone to tell me why. The biggest problem is the size of your overflow pipe. A 1 inch hose handles roughly 600 GPH. If you a 1800 GPH pump for a 180 gallon tank you have to use three 1” overflows or one 4” overflow. Noise is another problem when you have more flow than a pipe can handle. The water level will rise and then start to siphon causing a loud, sucking noise. Using various anti-noise devices reduces noise but it’s like putting a band-aid on a broken leg.  You need to use a pump that matches your overflow volumn.

To calculate approximate flow ratios is easy. Take the diameter of the 2 pipes you want to compare – let’s use 1” pipe and 2” pipe. Multiply the diameter by itself for each pipe. 1 X 1 = 1 AND 2 X 2 = 4. The ratio then is 1 to 4. A 2” pipe handles 4 times the water of a 1” pipe.


DIA.            RATIO      GPH
2”            2 X 2= 4.00   2400
1.5”   1.5 X 1.5= 2.25   1350
1”           1 X 1= 1.00     600
3/4” .75 X .75 = 0.56     335
1/2”     .5 X .5 = 0.25    150

The average coral tank needs lower flow than you think, SPS or Stony takes can’t handle super flow from powerheads, closed loop systems, and large return pumps which comes from a single direction .  On a reef there is surge only at very shallow depths, less than 3 feet.  Most corals come from much more than 3 feet.  Look at photos, movies, TV, etc. of coral reefs.  There isn’t tubulent water.  SPS like acroporas is one coral that grows in both low and high flow areas.  The famous Oregon Blue Tort likes lower flow.  I proved that in my shop.

WATTS PER GALLON really is misleading. The depth of the tank is most important followed by the requirement of the tanks inhabitants. (corals). If you put 500 watts over a low wide tank and the same 500 watts over a very tall tank, you get 2 very different light amounts at the bottom of the tank where it counts.  FYI Fish, rock, inverts do not need light.

POUNDS PER GALLON OF LIVE ROCK might work if only one type of rock were available. Since live rock comes from many locations around the world, you get different density and different forms of rock. Tonga rock is extremely dense, the total volume per pound is quite small. You can get a Fiji rock that is very spacious and takes up a lot of total volume per pound. You get much more for your money on the spacious, “lots of holes” rock even if it a few dollars more per pound. Landscape your tank the way you like it, not by some formula.  When I can get it Haiti rock is the best.  One customer came to buy 90 pounds and only took home 60 pounds.

DEEP SAND BEDS DO NOT de-nitrate as you might think. When you add over 1 inch of sand to a tank, the well oxygenated water doesn’t get to the lower sand. and Anaerobic conditions begin (no oxygen). The ocean has literally 1 million little creatures per square meter churning up the REAL live sand. Your deep sand bed will never have these nor is there a way to introduce them. Read my page on Research and discoveries

1 ANGEL PER TANK is one I disprove constantly in my holding tanks. My home aquarium started off many years ago with 13 different species of angels. All deaths were by natural causes. I don’t recommend 2 of the same species when the possibility of 2 males being put together is 25%, they MIGHT fight. I guess the fish never read the Internet.
See photo at the end of this page   

THE INFAMOUS OREGON BLUE TORT CORAL doesn’t like high flow conditions like many are led to believe.  I personally took a brown frag and placed it 14 inches from a 175W metal halide [5 inches was water] in bi-directional water with 125 gph alternating pumps.  In 3 weeks it had regained it’s color.  It’s growth rate averaged 2.5 mm per week once colored up and went from 4 spikes t0 9 in 3 months.

CLEAN UP CREW CRITTERS PER GALLON (crabs, snails, etc) are designed to empty your wallet. A clean up crew isn’t needed until the 2 stages of tank cycling algae are gone (1st reddish brown then a very tiny green- about 4 weeks). These critters are scavengers – don’t worry about feeding them. More “crew“ members starve or get eaten by other crew members who are bigger and hungrier than die naturally. 6 snails in a 100 gallon are enough. Arrow crabs are not safe to have. They will kill and eat shrimp, crabs, small fish and other small things.

FEEDING ANEMONES SILVERSIDES and krill is a sure fire way to starve them and pollute your tank. Anemones don’t have real stomachs, they secrete digestive juices. Very small to tiny pieces of food (brine or broken mysis) are much more easily digested. Anemones often grab enough food when the fish are fed to keep them well fed. See Feeding fish and inverts

RAISING THE TEMPERATURE TO KILL ICK works only if the tank is empty of fish, inverts and corals. Ick has a 6-10 day life cycle that depends on temperature. Higher temperature speeds up the cycle. If no fish are present, the parasites have no where to attach and grow. They then start dying off. If critters are present they are stressed by the heat and suffer or die. If your tank has ick and is empty, raise temperature to 85 for 3 weeks. That should kill off most parasites.

INCHES OF FISH PER GALLONS OF WATER is a freshwater rule of thumb because you can crowd freshwater fish.  Saltwater fish aren’t as sociable and you choose fish that swim and fish that are bottom dwellers.

USING WATER FROM AN ESTABLISHED TANK TO START A NEW TANK doesn’t do anything to speed the cycling of a new tank.  If anything it is adding dirty water to a clean, new system.  The possibility of transferring unwanted pests, diseases, and/or chemicals and contaminants exists.  DON’T DO IT.  Some stores sell “seasoned” or “coral” water from their tanks – you are paying for their water change in reality.

RAISING COPOPODS IN YOU REFUGIUM to feed your tank isn’t realistic because Pods would get ground up by the pump’s impellor.  The are not free swimming either and not likely to crawl into the intake.  Buying copepods isn’t worth it either.  There are 100’s of species naturally and you usually can buy one or two.  Also your tank never runs out of copepods, they are always in rock crevasses and in your sand/gravel.

LIVE ROCK doesn’t need light to survive.  Just circulating saltwater.

CARBON DOES NOT CAUSE LATERAL LINE DISEASE. Lack of the correct diet does.  Selcon is a great vitamin mix to use.  Thaw food without water, add 2 drops Selcon, mix and let soak 20 minutes than feed.

Carbon does not remove trace minerals. It does not remove phosphate. It will only remove very large organic molecules. Things that color the water are large molecules. Medications are large molecules.


THE IDEA THAT LEATHER CORAL should all be kept at the end of your tank where the overflow is to prevent them from poisoning other corals is ridiculous if you have any circulation in the tank. Any “toxic” effect will be spread dozens of times faster by internal pumps than it will be removed to your filter below. This also implies you cannot keep leathers unless you have a sump type filter – not true.  Toxins are released when cut during fragging.

A FAN BLOWING across a tank for cooling does not cause ick

Proof that you can have more than 1 angel in a tank

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