Why We Offer Two pH Dosers: Single Junction vs Double Junction

The Problem We Wanted to Solve

pH dosers have historically been expensive. The technology involved — precision amplification circuits, quality probes, reliable dosing pumps — adds up quickly. For commercial operations, the cost is justified. For hobbyists and smaller growers, it's been a barrier to entry.

We asked ourselves: does everyone actually need the highest-end components? Or is there a way to deliver reliable pH automation at a lower price point without compromising on what actually matters?

The answer came down to understanding what accuracy is actually useful in hydroponics — and what's overkill.

How Much Accuracy Do You Actually Need?

In practical hydroponics, the amount of accuracy that can be effectively utilised is about one tenth of a pH unit — a single decimal place. Measuring to 6.1 vs 6.2 matters. Measuring to 6.14 vs 6.15? Not so much.

Plants don't respond to hundredths of a pH point. Nutrient availability doesn't change meaningfully at that resolution. The extra decimal places look impressive on a display, but they don't translate to better results in your reservoir.

The same applies to temperature compensation. While it exists in high-end lab equipment, it's rarely necessary for hydroponic applications where solution temperatures are relatively stable.

The Handheld pH Meter Test

Most growers have used a handheld pH meter at some point. These typically use single junction probes and read to one decimal place. And as most people discover — they're more than accurate enough for hydroponics. Our entry-level doser uses similar technology, just in an automated package.

Single Junction: The Entry-Level Option

Our entry-level pH doser uses a single junction silver nitrate probe. This is the same technology found in quality handheld pH meters — proven, reliable, and effective.

What You Get

✓ One decimal place accuracy (0.1 pH)
✓ Reliable automated dosing
✓ Industrial single junction probe
✓ Cheap, easily sourced replacement probes
✓ ~60% of the price of our high-end model

Trade-offs

• More frequent calibration required
• Shorter probe lifespan
• Limited to single junction industrial probes
• No temperature compensation

This option exists because pH automation shouldn't be a luxury. If a handheld meter is accurate enough for you to manually adjust pH, the same probe technology is accurate enough to automate the process.

Double Junction: The High-End Option

Our premium pH doser uses a double junction probe paired with a high-impedance amplification circuit (over 1 gigaohm). This is laboratory-grade technology.

What Makes Double Junction Better?

The "junction" in a pH probe is where the reference electrolyte meets the solution being measured. In a single junction probe, this reference material is directly exposed to your nutrient solution. Over time, contaminants can seep in, causing drift and reducing accuracy.

A double junction probe adds a second barrier — an intermediate chamber between the reference electrolyte and the solution. This resists contamination for much longer, meaning:

• Half as many calibrations required
• Probe lifespan nearly doubled
• Reduced drift between calibrations
• Three decimal places of accuracy

Universal Probe Compatibility

The high-impedance amplification circuit in our premium model can work with any pH probe on the market — from basic industrial probes all the way up to the highest-end laboratory sensors. You're not locked into our ecosystem.

What Both Models Share

Regardless of which probe technology you choose, both pH dosers include the full OMGROW platform:

• Remote viewing and programming — check pH levels and adjust settings from anywhere via the web portal or app
• SMS and phone call alerts — get notified immediately if pH drifts outside your target range
• Historical data logging — track pH trends over time to identify patterns
• Independent operation — continues dosing even if your internet connection drops

Privacy and Security First

Despite all this integration, we are highly privacy focused. All software is written by an extremely security-conscious developer. Your data stays yours — we don't sell it, share it, or use it for anything other than running your system.

Probes Are Consumables

Here's something worth remembering: all pH probes are consumables. Even the highest quality double junction probe, perfectly maintained, will not last more than a year or two in continuous use.

The reference electrolyte depletes. The glass membrane ages. The junction clogs. This is inevitable. The question isn't whether you'll replace the probe — it's how often, and at what cost.

With our single junction option, you'll replace probes more frequently — but each probe costs significantly less. With our double junction option, probes last longer but cost more. Over time, the total cost of ownership is similar. The difference is in convenience and the precision you need.

Which One Should You Choose?

Feature	Single Junction	Double Junction
Accuracy	1 decimal place (0.1 pH)	3 decimal places (0.001 pH)
Calibration frequency	More frequent	Half as often
Probe lifespan	Shorter	Nearly 2× longer
Probe compatibility	Single junction industrial	Any pH probe
Replacement probe cost	Lower	Higher
Price	~60% of high-end	Premium

Choose Single Junction If:

• You're on a budget
• You're comfortable with more frequent calibration
• You're happy with 0.1 pH accuracy
• You want the lowest barrier to entry

Choose Double Junction If:

• You want less maintenance
• You prefer longer probe lifespan
• You want to use any probe on the market
• You're running a commercial operation

Both Options Work

We wouldn't sell the single junction model if it didn't do the job exceptionally well — with more than enough reliability and accuracy for hydroponics. It automates a task that not only required daily attention, but stretches the human user's discipline. pH management often gets overlooked because of time constraints or convenience. It's always best to automate these kinds of weak points out of your system if possible.

The double junction model is for those who want the best — longer intervals between maintenance, compatibility with any probe, and the precision of laboratory equipment.

Either way, you're getting automated pH control with remote monitoring, alerts, and the peace of mind that comes from knowing your reservoir is being managed around the clock — an invaluable shortcut in the grow room that leads to much more reliable outcomes, almost always.