Measure Master Pump 1 Ounce Dispenser – Gallon Jug

The Measure Master Pump 1 Ounce Dispenser is a screw-on hand pump for standard 1-gallon nutrient bottles that delivers exactly one fluid ounce (29.57 ml) per stroke. Polypropylene body, stainless steel internals, and a 38/400 thread that fits the same cap as most one-gallon liquid plant food and supplement jugs. Threaded body disassembles for fast, sanitary cleaning between products — no more pouring, no more guesswork on cap-fill volumes.

Measure Master 1 oz Pump Dispenser Specifications

A small, single-purpose tool aimed at one job: getting an exact ounce out of a gallon nutrient jug without spilling, without rinsing a measuring cup, and without contaminating the bottle. The pump screws onto any standard 1-gallon nutrient container with a 38/400 cap thread.

Why Choose the Measure Master 1 oz Pump Dispenser

Measure Master calls itself the “Trusted Partner for Precision Measuring Equipment” — functional, repeatable, no marketing fluff. The 1 oz pump dispenser is the cheapest tool in their line and one of the most-used items on a serious grower’s nutrient shelf. Here is why it earns the bench space:

• One pump, one ounce, every time. Most nutrient recipes are written in oz/gal — FloraGro 3 oz/gal, Bloom Booster 1 oz/gal, Cal-Mag 1 oz/gal. The pump removes the math: one stroke equals one ounce, and there is no measuring cup to rinse between products.
• Polypropylene + stainless steel survives the chemistry. Liquid plant nutrients are aggressive — phosphoric acid in pH Down, EDTA-chelated micronutrients, surfactants, dense salt solutions. Cheap pumps with mild steel springs corrode and seize inside a season. Polypropylene shrugs off acids and bases; stainless springs do not rust in the wet, salty environment around a reservoir.
• 38/400 thread fits the bottle you already own. The 38/400 is the standard 1-gallon HDPE jug cap used across nearly every major hydroponic nutrient brand — General Hydroponics, Botanicare, Cutting Edge, House & Garden, Roots Organics, Heavy 16. Unscrew the factory cap, screw on the pump, done.
• Threaded body disassembles for cleaning. Salt build-up is the silent killer of pumps. Once a week (or when switching nutrients), unscrew the housing, rinse the piston and spring in warm water, dry, reassemble. Five minutes; the pump lasts years.
• No more lost caps and sticky shelves. A capped jug stays clean and pours cleanly the first time. The pump replaces the cap, the cap goes in a drawer, and the jug stays upright and labeled where it belongs.
• Cheap enough to keep one per bottle. At under six dollars, the right answer for a multi-bottle nutrient program is to assign one dedicated pump to each jug — FloraGro pump stays on the FloraGro bottle, Bloom pump stays on the Bloom bottle — eliminating cross-contamination entirely.

Best Uses for the 1 oz Pump Dispenser

This is a routine, daily-use tool for any grow that mixes liquid nutrients into a reservoir or watering can. The most common day-to-day jobs:

• Mixing a 3-part nutrient feed. FloraMicro, FloraGro, and FloraBloom are dosed in ounces per gallon. Three jugs, three dedicated pumps, count strokes into the reservoir, stir, done. No measuring cup, no spillover.
• Cal-Mag at 1 oz/gallon. Cal-Mag is the most common 1 oz/gal additive in hydroponic recipes — calcium nitrate, magnesium nitrate, and chelated iron. One pump per gallon of reservoir water is the easiest dose to remember.
• Bloom boosters, root supplements, and beneficials. Many high-P bloom boosters dose at 1–2 oz/gal during flower. A pump on the bottle means you grab, pump twice, and move on without breaking flow.
• pH Down / pH Up dispensing. Phosphoric acid based pH Down is corrosive on hands and equipment. A 1 oz pump dispenses a precise dose into a reservoir without ever opening the cap or touching the liquid. Wear gloves anyway.
• Filling a watering can or hand sprayer. Quick foliar spray needs 1–2 oz of concentrate into a gallon sprayer — pump it directly, top with water, shake, spray.
• Refilling smaller bottles from a 1-gallon master jug. Buying nutrients by the gallon is cheaper per ounce than by the quart, but most growers want a quart-sized bottle on the bench. Pump-fill the small bottle from the gallon; keep the gallon sealed in storage.

Measure Master 1 oz Pump vs Generic Pump and Garden Syringe

Three common ways to get exactly one ounce of liquid nutrient out of a gallon jug. Honest trade-offs:

Bottom line: if a recipe is in oz/gal and the bottle is a 1-gallon jug, the dedicated pump is the right answer — one pump per jug, label it with a Sharpie, and the nutrient routine drops from a five-minute clean-up to a thirty-second pour. For sub-ounce or PGR work, reach for the syringe instead.

Compatibility & What It Pairs With

The pump is a single-purpose accessory; the value comes from what it screws onto. A practical pairing checklist:

• 1-gallon nutrient jugs with 38/400 caps: the dominant cap size on hydroponic 1-gallon liquid nutrients. General Hydroponics FloraGro/Micro/Bloom, Botanicare Pure Blend, Cutting Edge Solutions, House & Garden, Heavy 16, Roots Organics liquid line, and most pH Up/Down 1-gallon bottles. Unscrew the factory cap, screw on the pump.
• Pair with a precision scale for mixed recipes: when a recipe combines liquid (oz/gal via pump) and dry amendments (g/gal), the natural counterpart is a benchtop scale like the Measure Master 5000g digital scale. Pump the liquids first, weigh the dry adds second, stir all into the reservoir.
• Pair with a graduated bucket for batch mixing: if you mix five-gallon batches at a time, the Measure Master 5 gallon graduated measuring bucket reads the gallon line directly — fill, pump in five strokes per gallon for a 1 oz/gal additive, stir.
• Storage: leave the pump on the bottle between feeds. The cap is internal to the pump housing — closing the lever blocks the dispense path, which is enough to slow evaporation and keep the spout clean.
• NOT compatible: 2.5-gallon nutrient jugs use a 63/485 cap thread — the pump will not screw on. For 2.5-gallon containers, choose Measure Master’s related model #740042 (sold separately). Pint, quart, and 0.5 gallon bottles also use different thread sizes; the pump will spin freely on them.
• Chemical cautions: safe with the vast majority of liquid hydroponic fertilizers, supplements, and pH adjusters. Avoid using the same pump with strong oxidizers like concentrated bleach or undiluted hydrogen peroxide above 3% — oxidizers degrade the seals over time.

Usage Steps for Routine Nutrient Mixing

The pump is designed for fast, one-handed operation right at the reservoir. Full sequence for a routine feed:

1. Unscrew the factory cap from the 1-gallon nutrient bottle. Keep the cap somewhere safe — you will want it back for long-term storage if the bottle sits unused for months.
2. Screw the pump onto the bottle by hand. Tighten until snug; do not over-torque or the threads can strip on the soft polypropylene neck.
3. Prime the pump. First time on a new bottle, the dip tube is dry. Press and release the head 4–6 times until liquid starts flowing through the spout. Discard the first half-pump (it may be air-filled) by pumping into a rinse cup.
4. Position the spout over the reservoir or watering can. The spout extends past most reservoir rims; aim it directly at the water surface to avoid splashing.
5. Press the pump head fully down once per ounce. Each complete stroke delivers exactly 1 oz (29.57 ml). Two pumps for 2 oz, three for 3 oz, and so on.
6. Count out loud. Easy to lose track if interrupted mid-feed. Say the stroke number aloud as you go.
7. Repeat for each additive. Move to the next bottle, pump, count, move on. One pump dedicated to each bottle eliminates rinsing between products.
8. Stir the reservoir thoroughly after all liquids are added. Pumped doses are concentrated drops — without stirring, plant roots near the input point get a localized overdose.

How to Clean and Maintain the Pump

The pump is designed to be field-serviced — the threaded body disassembles by hand, with no tools. A few habits keep the dosing accurate and the spring rust-free for years:

1. Rinse the spout daily. A quick burst of clean water through the pump — pump into a rinse cup for 3–5 strokes — flushes residual nutrient that would otherwise crystallize on the spout overnight.
2. Deep-clean weekly. Unscrew the pump from the bottle. Unscrew the threaded housing to expose the piston, spring, and seals. Rinse each part under warm running water. Inspect the spring — stainless should still be bright; any rust or pitting means the pump has been exposed to undiluted oxidizers and the spring should be replaced (or the pump retired).
3. Clean between products. If you must move the pump from one bottle to another (e.g., bottle empty, transferring pump to a new jug), pump 5–10 times of warm water through the housing, then 3–5 of dry air strokes to clear the dip tube. Cross-contamination is the most common cause of unexplained nutrient lock-out in a multi-bottle program.
4. Air-dry before reassembly. Salt water inside a closed housing accelerates corrosion. Lay the parts on a clean towel for ten minutes before screwing back together.
5. Check the dose monthly. Pump into a calibrated measuring cup or graduated cylinder. A fresh, full-prime pump should deliver 29–30 ml per stroke. If the volume has drifted below 25 ml, the spring is fatigued or seals are worn — replace the pump.
6. Never run dry for storage. If a bottle is finishing up and you want to swap the pump to a new jug, do not store the pump dry on a shelf — the seals stiffen and crack. Park it in a small jar of clean water if the next bottle is a week away.
7. Do not autoclave or boil. Polypropylene softens around 100°C; hot soapy water in a sink is the upper limit. The spring will not be damaged by heat, but the body will warp and the dose accuracy will drift.
8. Retire and replace. A well-maintained pump lasts 2–3 years of daily use. Cracked housing, drifted dose, or visible spring corrosion are all replacement triggers. At under six dollars, replacement is cheaper than guessing.

Sources & Further Reading

1. HGS Hydro — Measure Master brand collection (hgshydro.com)
2. HGS Hydro — hydroponic supply home (hgshydro.com)