Tanks & Reservoirs

Picking reservoir volume for the system

Reservoir size comes down to two numbers: how much solution the plants take between changes, and how much pH, EC and temperature swing you will live with. A small tank moves every time the plants drink, and it follows the room temperature almost immediately. Extra litres slow both of those down and make the tank easier to manage. Most growers size for the plants, then take the next size up.

The figure on the label is not the working volume. PLANT!T publish both: the 100L tank holds 90L in use, the 60L holds 50L and the 500L holds 450L. Keep that spare so the solution stays above the pump inlet — once the pump starts pulling air at the end of a feed, you have gone too low.

What's in the tanks and reservoirs range

Sea-Hawk Hydro Tanks

These are flexible, foldable tanks made for hydroponic work, stocked from 100L to 380L. The 100L stands 78cm tall on a 40cm diameter; the 200L is shorter and wider at 70cm by 60cm, which is the shape that fits under a bench. Sea-Hawk say the tanks help hold water temperature and pH steady and connect easily to hydroponic systems.

PLANT!T Flexible Tanks

Four sizes, 60L to 500L. They assemble without tools and every size includes a 13mm nut and tail on a ¾-inch BSP thread, so the outlet is already there when you start plumbing. The 250L is 60cm across and 90cm high; the 500L is 70cm across and a metre tall.

Bloom Works FlexiFlow

Heavy-duty reinforced PVC in 100L, 225L and 500L, UV-resistant with reinforced seams. Each tank comes with support frame rods that hold its shape when full, a zipper-sealed lid, and an outlet and drain valve — which is why these are the easiest of the three to empty and refill without tipping.

Why lids and lightproof tanks matter

Algae starts when nutrient solution and light share the same space. It uses up oxygen, clogs pumps, drippers and air stones, and a clean tank can smell within a week. Cut the light and the problem stops: a closed lid, an opaque tank, and no gap a grow light can reach. The FlexiFlow zipper-sealed lid is built for that, and Blumat say the same in their instructions — use a lightproof tank and clean it periodically so fittings do not clog.

Five checks before you buy a reservoir

1. Size from feed volume, then step up one. A tank that sits near empty is exactly the pH and EC swing a reservoir is meant to prevent.
2. Measure the footprint, not only the litres. Same capacity, different shapes — the 100L Sea-Hawk is tall and narrow, the 200L short and wide.
3. Know which outlet comes with the tank. PLANT!T include a 13mm nut and tail on a ¾-inch BSP thread; Bloom Works include an outlet and drain valve. Pair them with hose and fittings on the irrigation page.
4. Decide if the tank has to fold. Collapsible tanks pack flat between crops and move without a trailer, which is why this range is built this way.
5. Check what the tank will sit on. A full 500L tank is half a tonne of water. It needs a flat, load-bearing floor, and gravity-fed setups need height as well.

Once the tank is sitting, empty it from the water pumps page, aerate standing solution from the hydroponic air pumps page, and if an Australian summer pushes the temperature up, that is the water chillers and heaters range.