Underwater, High-Flow Float Valve: Meet the Vortex Bottom Fill

Most float valves assume there's room to mount above the water line, at or near the top of the tank wall. Not every installation has that luxury. Low-clearance tanks, setups where the hardware needs to stay completely out of reach, or tanks where an above-water mount just doesn't fit the geometry all run into the same wall — literally. The Vortex Bottom Fill exists for exactly that situation: a high-flow valve configured for underwater mounting only, installed through the side wall or the floor of the tank and staying fully submerged.

Fully Submerged Isn't a Limitation Here — It's the Design

Unlike valves that mount above or below the waterline depending on the install, Bottom Fill is built specifically to stay underwater. That has real advantages beyond just fitting a tight space: a submerged valve is physically out of reach of livestock, protected from impact and weather, and insulated against freezing by the surrounding water. It's the same underwater-first logic that makes Megaflow well-suited to livestock troughs, applied to Vortex's higher-flow platform instead.

How It Actually Fills the Tank

A nylon cord connects the float to the valve rather than a rigid arm, operating a pilot valve that triggers the main diaphragm as the water level drops. That's the same two-stage pilot-and-diaphragm mechanism the rest of the Vortex line uses — a small, precise motion at the float controlling a much larger flow of water downstream — just configured to sit underwater instead of above the water line.

Side Entry or Bottom Entry

Bottom Fill is underwater either way, and you choose the entry point to suit the tank. In a side-entry installation the valve is mounted horizontally through the tank wall, below the water line. In a bottom-entry installation it's mounted vertically through the tank floor. Either way, the float rides on its cord above the valve and the whole assembly stays submerged. That flexibility across different tank shapes and layouts is a big part of why Bottom Fill works where a conventional valve can't.

Built the Same Way as the Rest of the Vortex Line

Bottom Fill carries the same construction the Vortex line is built on — compact, robust, corrosion-resistant — and the same practical features: the valve unscrews from its tail for tool-free service access, a lock-off switch shuts it down for maintenance without touching the main supply, and a port accepts the Frost Pro anti-freeze device for cold climates. Its differential (3/4"–2.5", or 20–60mm) widens as inlet pressure increases, and a slow shut-down mechanism minimizes water hammer — a real concern at the flow rates this valve is capable of.

Sizing It Correctly

Bottom Fill is available in 1.25", 1.5", and 2" inlets. As with every Jobe valve, match the inlet to your actual supply plumbing — a 2" valve won't outperform a 1" supply line, since flow is always capped by the smallest pipe in the system. Vortex uses a threaded tail rather than the swappable Detach system on Topaz and Megaflow, but that doesn't mean you're locked in: a replacement Vortex tail is available in all three sizes, so if your plumbing changes down the road, you can swap the tail instead of replacing the whole valve.

Where It Fits

Bottom Fill makes the most sense on livestock troughs and water storage tanks where an above-water mount isn't practical — low-profile tanks, setups where the valve needs to be fully concealed, or installations where underwater protection from animals and weather is a priority alongside high flow. If your tank has room for a conventional above-water valve, the standard Vortex is simpler to install and service. Bottom Fill is the answer specifically when "on top" isn't an option.