Q. I have enclosed a detailed description of my tank setup and conditions, as well as photos of my fancy fantail goldfish. They all appear to be happy and healthy, their behavior is normal, as are their appetites. My two orange fish have lost some scales, the two calicos have not. All four fish have grown since I upgraded to a larger tank last September. Do goldfish molt? Could their recent, rapid growth cause scale loss?

I looked through my disease reference charts and found no mention of scale loss. There are no visible scratches, sores, spots or other signs of injury, and the fish do not fight. I noticed the condition about a month ago. The pH was down to 6.6. I added 1 teaspoon of StressCoat to the water, plus a dose of pH Plus. I did a 30-percent water change and added more StressCoat and more pH Plus. I also lowered the water temperature from 76 to 74 degrees Fahrenheit.

A week later I did a 50-percent water change, thoroughly vacuumed the gravel and changed the filter. Also, (after seeing a copy of the November 1994 AFI article about using salt to relieve stress) I added Doc Wellfish's Aquarium Salt (4 teaspoons for 20 gallons). I noticed no change after either treatment. The scale loss is no better, nor any worse. Since then I've done two partial water changes using bottled water because my water softener is not working (170 to 210 parts per million. I've added nothing but salt to the water. Any suggestions?

Today I noticed that one of the orange fish has a torn tail fin. It looks like it might have been torn on something, but I do not know what.

A. I think we can solve the mystery here pretty quickly. The writer included a full-page outline of his goldfish aquarium setup with his letter, which helped a lot in analyzing the problem. He provided information on tank dimensions, water capacity, filtering system, aeration, decor (very important for considering physical incompatibilities), fish, water conditions, water change schedule and procedure, and feeding schedule.

Scale loss is not normal for goldfish. They do not molt. Most often scale loss is the result of physical injury — banging against hard objects in the tank (especially during breeding season) or rough handling. It may also result from skin infections, but in this latter instance clear signs of skin deterioration, bleeding and so on are obvious.

Given the time of year (winter), size (age) and type of goldfish, and the tank conditions, it is very unlikely that violent breeding activity caused the scale loss. These fish are not particularly violent breeders anyway. They cannot generate the speeds that regular goldfish can, so scale loss from breeding is less likely.

The most telling piece of information was listed under "Fish." The writer has a 3-inch (excluding tail) pleco of unknown species in the tank. Plecos suck on the slime coat of goldfish and do remove scales. The photographs the writer provided show patterns consistent with this. The split tail could be a consequence of pleco "attacks" or might be a sign of stress.

In either case the pleco has to go. These physical injuries provide a dangerous opening in the fish's outer protection against bacterial and fungal infection. Dallas' first-rate water quality management — especially using salt — probably prevented serious disease from taking hold. Moreover, the salt helped the fish maintain its internal chemical balance despite its wounds.

About That Pond Plumbing Article
Q. Thank you for the very informative article on pond plumbing in the September 1995 issue. It should provide a good starting point for people who are trying to plumb a pond. Unfortunately, it reiterated a common misconception that we, as a manufacturer of pumps for both industrial and pond applications, often hear: use pipe the same diameter as the pump port. This simply is not so.

The diameter of the pipe selected should be based on the desired flow rate, the layout and the overall length of the pipe you will be using. This will determine friction losses and resulting overall head that must be overcome by the pump. To minimize friction losses use larger diameter pipe, especially for longer runs.

The article says that nothing is gained by using pipe larger than the pump port size. This also is not true. Larger diameter pipe lowers the friction loss of water through that pipe and the overall back pressure or head against the pump, thus increasing the flow rate. This means a higher flow rate from the pump and greater electrical efficiency. Using too small a diameter pipe is such a common mistake by many first-time pond builders that we really hope you can educate them on this point.

A. In theory, this writer is correct. One can use pipe size to regulate the flow from a pump. If you use a pipe diameter smaller than the outlet of your pump it will restrict the flow. Most ponds suffer from too little flow (recirculation). If you do have too much flow, get a smaller pump.

If you want to restrict the flow on a pump you already own, it's much wiser to use a ball valve at the pump outlet. This would give you the flexibility to vary flow through the system without permanently restricting the flow rate should you want a higher flow rate later on.

In fact, adding a ball valve at the pump outlet is a good idea in general. A contributing factor to clogged piping systems is consistent flow. Algae, detritus and other forms of aquatic gunk stick to pipe walls and narrow the flow path. Varying the flow through the system every couple of days by slightly opening and closing a ball valve will help keep the pipe clean.

Whether or not piping larger than the pump outlet offers a significant advantage in reducing friction depends on the specifics of the setup. For example, if you are using pipe with a coarse inner surface — in particular, ribbed swimming pool tubing — then using a larger-size pipe can make a big difference. In typical ornamental pond applications, however, with relatively short rises and runs through smooth piping, actual gains by "up-sizing" will be small. One of my ponds uses a Multi-Duti Sequence 1000 pump with a 1-inch port. The piping system runs about 100 feet to an elevation about 4 or 5 feet above the pump. Switching to 2-inch PVC pipe makes a small measurable difference in flow rate — but not one that justifies the added cost of 2-inch flexible PVC pipe.

Nevertheless, his objection is well taken, and pondkeepers might find they can eke out a few more gallons per hour if they use piping a bit wider than the outlet port on their pumps. Moreover, I would also suggest that those of you with very small pumps — outlet ports of ½ or ¾ inches — might be best served by using 1-inch pipe. The smaller pipes are highly prone to clogging and narrowing.

I'd also like to put in a plug for Multi-Duti pumps in general. Their Sequence 1000 pump looks like a standard horsepower swimming pool pump, but it is not. I have found that it uses about half the electricity of a typical swimming pool pump. Although the Sequence 1000 is about three times the price, here in the Northeast where electricity is about 11 cents per kilowatt hour it pays for itself in about two to three years. All the Multi-Duti pumps I have installed continue to run flawlessly — and they are quiet too!

Pushing for Natives
Q. I noticed in many of your articles and columns that you emphasize landscaping a pond with native plants. I find this odd given the large variety of ornamental shrubs available at nurseries and the fact that most landscaping is done with non-native plants. Are native plants those you can find growing wild in the area, and why push native plants?

A. Yes, I do push native plants. One reason is that in most instances they are more tolerant of variations in local weather, so they present fewer maintenance problems over the long term.

Also, native plants almost always have special relationships with local wildlife. In some cases there are intense "mutualisms" — each needs the other to survive. Therefore, landscaping with native plants enhances native wildlife potential and reduces the risk of endangering certain animal species.

Correspondingly, attracting native wildlife to your pond implies using native plants in landscaping. Having evolved along with those plants, local wildlife will more easily adapt to cover and food in a setting landscaped with native plants.

Unfortunately, many plants found growing wild in the United States today are not native to their locale. These "exotics" are the escaped offspring of transplanted ornamentals. This is especially true in warmer climates. Worse, some out-compete native plants, effectively wiping them out. Local wildlife extinctions of animal species dependent on those plants usually follow. Therefore, "native" and "locally wild" are not the same. For information on true native plants, contact your local garden club, wildflower society or state Fish and Wildlife department.