PRODUCT REVIEW		RICHARD HARKER

RICHARD HARKER

Duetto DJ-50

Inexpensive Chemical Filtration

Perhaps one of the more attractive reasons for passive use of carbon is the simplicity of it. Before passive use became popular, the normal method of carbon use was to place a large amount of carbon in an expensive cannister filter or attach a pump to some sort of reactor to circulate water through the carbon. Both methods required greater effort and expense than the passive approach.

Active carbon use need not be difficult or expensive. A number of manufacturers offer inexpensive submersible filters that can be adapted to provide convenient and effective chemical filtration for most tanks. In this review, I'll examine two submersible filters, the Fluval Power Filter and the Aquarium Systems Duetto Multi-Filter.

As outlined in the article, most hobbyist-oriented books recommend that hobbyists use a great deal of carbon. There is convincing evidence, however, that a small amount of carbon is all the aquarist needs to avoid an accumulation of yellowing compounds. As little as 3 tablespoons are enough for up to a 50-gallon tank. Furthermore, a very slow water flow through the carbon is far more effective than a rapid flow. Even the smallest internal filters provide adequate space for sufficient carbon and a slow rate that maximizes filtering.

RICHARD HARKER

Optional hose barb for the Duetto DJ-50

Aquarium Systems’ Duetto Multi-Filter

The DJ-50 stands only 5 1/2 inches tall and 1 1/2 inches wide, and can be operated standing up or laying on its side. Three suction cups on the unit’s side enable the filter to be mounted on the side of the sump. In a shallow sump, it can be mounted horizontally, while in a sump with at least 5 inches of water, the unit can be mounted upright. The unit consumes only 4 watts. The water flow rate can be varied from 13 to 66 gallons per hour.

Used as a carbon filter for a reef tank, the foam filter and carbon cartridge should be removed from the Duetto DJ-50. Instead, activated carbon placed in a small mesh bag should be placed in the filter. The DJ-50 can hold up to 36 grams of carbon, about 8 tablespoons. This may seem like a small amount, but it is more than enough carbon for a 90-gallon reef tank. The small foam prefilter can be retained to keep detritus from clogging the carbon.

RICHARD HARKER

Fluval 1 Internal Cartridge Filter

The Duetto DJ-100 is considerably larger than the DJ-50. It can hold a larger amount of carbon and pump water at a higher rate, up to 92 gallons per hour. Power consumption is 2 watts higher than for the DJ-50. While the larger unit is unnecessary for most hobbyists, those still clinging to the old recommendation for large amounts of carbon may prefer this unit.

Fluval Internal Cartridge Filter

The Fluval 1 is a more basic unit compared to the Duetto. The filter compartment is one large unit and lacks the Duetto’s prefilter section. Flow direction is not adjustable. The smallest Fluval does not come with hose barbs. However, larger units do have hose barbs and the direction of flow can be varied. None of the units has variable flow rates. These drawbacks are of minor consideration when the filter is going to be used in a reef tank sump.

RICHARD HARKER

The Fluval submersibles can be mounted using either suctin cups or a clamp that hooks over the rim of the tank.

It does have two advantages over the Duetto for use in a reef tank. First, it has a larger capacity for holding carbon. The Fluval 1 can hold almost 2/3 cup of activated carbon, nearly 50 grams, placed in a mesh bag. This is enough carbon for all but the largest of reef tanks.

A second advantage is the mounting options available with the Fluval units. The Fluval submersible filters can be mounted like most powerheads, using either suctions cups or a clamp that hooks over the rim of the tank. The suction cup or clamp bracket is attached to the side of the tank and then the filter slides into the bracket. Using either method the filter can be easily removed from the tank to be refilled. In contrast, the Duetto mounts with attached suction cups, making it more inconvenient to remove the unit from the wall or bottom of the tank.

The biggest disadvantage of the Fluval units is the high rate of water flow. To maximize the effectiveness of activated carbon, water should just trickle through the filter. The Duetto flow rates are more appropriate for carbon use.

Either unit can be purchased for less than $30, considerably less than the more traditional cannister filters or carbon reactors normally used. They occupy considerably less space than cannister filters, and can be used in the sump rather than attached to the display tank. There is no additional equipment to purchase or maintain. Equally importantly, flow rates of either submersible filter are a fraction of most cannister filters, making them more effective for chemical filtration.