Fish

From a desk tank to a pond in the garden:

the branches under fish split by where the water sits. Aquariums and aquarium accessories is the tank itself and what goes on it: glass, stand, lid, light and filter. Aquarium fish gathers the smaller kit that keeps a tank going, such as heaters, thermometers, nets and the bags and boxes used when a tank has to move. Pond fish is the outdoor side: liners, submersible pumps, pressure filters, UV clarifiers, and the netting that herons and kingfishers persuade most pond owners to buy. All three share the same unglamorous gear, the water treatment and testing that decides whether the rest works.

Hard water on the coast, soft water inland:

the tap you fill from matters more to the equipment than most people expect. The interior, Central Valley included, runs mostly on soft water. Much of the coast does not: around Santa Cruz, Carrillo, Parrita and Corredores the water is hard enough to scale household pipes, while Liberia, oddly, stays soft. On hard water a white crust builds at the waterline, under the lid, around the glass tube of a heater and on a pump’s impeller shaft, and a UV clarifier weakens as its quartz sleeve clouds over. White vinegar and an old toothbrush lift most of it, and doing it with every filter clean saves a seized pump. Soft water has the opposite habit: it holds little buffering, so the pH can slide between water changes, and a KH test shows when. Wherever you live, mains water from AyA and most ASADAS is chlorinated, which makes water conditioner the one bottle no tank goes without.

Test kits, conditioner and a reverse-osmosis unit:

strips are quick, liquid kits are more reliable, and both carry a date. Strips spoil fastest once the tube has been opened and left uncapped. A reverse-osmosis unit earns its place mainly on the hard coastal water, or anywhere for a reef tank, since tap water carries more than corals tolerate. Its sediment and carbon prefilters are changed regularly and the membrane less often, and hard water wears the membrane out sooner. Add a gravel siphon and a bucket kept for the tank alone, one that has never held soap or floor cleaner.

A used pump, heater or UV clarifier:

plug the pump in with its intake in a bucket of water: it should start at once and run with an even hum. Pull the impeller and spin it by hand; it should turn freely on a clean shaft, and white scale there tells you the pump spent its life on hard water. A heater’s glass tube should be free of hairline cracks, and its indicator light should go off as you turn the dial down. On a UV clarifier, ask when the bulb was last changed, because a bulb that still lights up is not necessarily still working, and look through the quartz sleeve for crust. Check the date on any test kit or opened bottle of conditioner that comes with a set-up. With a pond liner, unfold it and look along the old creases: EPDM rubber stays supple for years, while PVC stiffens and splits along the folds.

Before a filter or pond pump goes up for sale:

note the make and model and the tank or pond size each piece is rated for, because buyers match a filter to the volume of water, not to its looks. Say which water it ran on, coast or interior, and whether it has been descaled. A short video of the pump or filter running in a bucket settles more than a paragraph of description. For a full set-up, list what goes with it: light, heater, lid, siphon and spare sponges, and photograph the dates on anything sealed. Someone driving from Corredores for a pond pump will want to watch it run before loading it, so keep a bucket of water ready by the door.