20 gallon long vs 20 gallon high

The light is the purchase this decision actually changes, and this is the fixture that makes the decision reversible. Buy a 24 to 30 inch adjustable fixture and the tank underneath it can be either shape, now or after an upgrade.

The built-in timer is the feature worth paying for, and not for convenience. A consistent photoperiod is the single biggest lever a beginner has over algae, and a fixture that switches itself on and off at the same time every day removes the variable entirely rather than relying on you.

Dimming matters more on the high than on the long, because four extra inches of water is four more inches for light to lose intensity through. On the long, the same fixture sits closer to the substrate and you are more likely to want it turned down.

The honest costs. hygger publishes no PAR or lumen figure we can verify, so none is printed here. A built-in timer is one more thing that can fail, and when it does the fixture usually still works while the schedule does not — a plug-in timer fails more gracefully. Clip-on brackets want a rimless or thin-rimmed edge.

If the tank is a fish tank with a couple of hardy plants in it rather than a planted display, this is the honest amount to spend on lighting, and it keeps the same both-footprints flexibility as the pick above.

A budget fixture buys the same thing an expensive one does for the first year: visibility, a day and night cycle, and enough light for low-demand species. What it does not buy is control.

The honest costs. No published output figures at all, which is why it is not the first pick despite the price. No timer and no dimming, so your only lever on the photoperiod is a wall timer bought separately — which works, but it is blunt, and on a 20 long with the light sitting closer to the plants that bluntness shows sooner.

This is the fixture our 10 gallon lighting page recommends, and the bracket range is why it reappears whenever the tank is 24 inches: the same light covers a 10 gallon tank and a 20 gallon high.

It belongs on this page specifically as the cost of committing. If you are certain the tank is the high, this is a cheaper light than either flexible option. If you are not certain, the saving disappears the moment you buy the longer tank.

The honest costs. It does not fit a 20 gallon long, and at 24.25 inches the high is at the limit of the stated bracket range rather than comfortably inside it. No built-in timer, so budget for a plug-in one. NICREW publishes no PAR figure we can verify, so none is printed, and 15 W will not grow a carpeting plant through 15 inches of water on a 20 high.

Wattage does not change with the shape, because wattage follows volume and the room, not the footprint. Both tanks hold 20 gallons, so both want about 100 W in a normal room. This is the same heater our 20 gallon page lands on, for the same reason: Eheim publishes a control accuracy tolerance and almost nobody else in this class does.

What the shape changes is how it mounts. The published length is 12.5 inches and a 20 gallon long is 12.75 inches tall externally, which leaves less water than that once the rim and the fill line are accounted for. In a 20 long this heater goes in horizontally along the back glass. That is a normal way to mount a heater, not a fault, but it is worth knowing before the box is open.

In a 20 gallon high the same unit hangs vertically with room to spare, which is the easier installation and keeps the element away from the substrate.

The honest costs. Glass-bodied, so it breaks if you knock it against the rim or leave it exposed while the tank is drained — the usual way these die. Horizontal mounting in a shallow tank puts it closer to the substrate and more in the way of a gravel vacuum. And no thermometer is included, which on an adjustable heater is not optional.

This is here to make the trade explicit rather than to recommend it blindly. In a 20 gallon long, the heater that fits upright is underpowered and the heater that is correctly powered has to lie down. There is no unit in this line that is both.

Buy it only if you have measured your room on a cold morning and it genuinely stays warm. In a house that drops to 68 F overnight this runs continuously through winter and still sits a couple of degrees low, which is the quiet failure that gets blamed on the fish rather than the heater.

Everything else is identical to the 100 W model: the same 18 to 34 C adjustment range, the same stated plus or minus 0.5 C control accuracy, the same user recalibration. Eheim changes the element between sizes, not the thermostat.

The honest costs. The wattage is the cost. It is also glass-bodied, carries no thermometer, and Eheim publishes no per-wattage gallon rating, so the sizing above is our arithmetic rather than a claim on the box.

This is a skip on shape, not on quality. On a planted 20 gallon high it is the step up worth paying for: Fluval's planted line is built around spectrum and programmable intensity rather than raw brightness, and ramping plus a custom schedule are real tools for managing algae.

The problem is the number on the box. This version is stated to fit 15 to 24 inch tanks. A 20 gallon long is 30.25 inches, so roughly six inches of tank sit outside the fixture — which on a planted tank means the far end grows differently from the middle.

Fluval sells a longer version of the same fixture. If you want this light on a 20 long, buy that one instead; what you must not do is buy this one and assume a fixture sold for a 20 gallon tank fits every 20 gallon tank.

Worth saying plainly: on a low-tech tank running java fern, anubias and cryptocorynes, this fixture will not grow anything the 15 W option cannot. It costs several times as much, and more light without the nutrients to match is a reliable way to grow algae rather than plants.