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Bluelab pH PenPlus in white and blue with backlit LCD screen, lanyard loop, and replaceable blue probe, shown against a white background. Hands unscrewing the replaceable blue probe from a Bluelab pH PenPlus in a greenhouse. Grower testing the pH of a runoff sample in a beaker with the Bluelab pH PenPlus beside greenhouse pepper plants. Bluelab pH PenPlus standing in a beaker of nutrient runoff next to passion fruit growing in a greenhouse. Grower reading the Bluelab pH PenPlus display at the open hatch of a nutrient tank. Bluelab pH PenPlus probe dipped directly into a hydroponic reservoir beside a float valve. Hand holding a Bluelab pH PenPlus next to the opening of a white nutrient reservoir tank. Grower spot-checking reservoir pH with the Bluelab pH PenPlus in front of a wall of monitoring and dosing equipment.

Bluelab pH PenPlus, Waterproof with Replaceable Probe

Bluelab
Price:
$115.00
Contact us about commercial pricing
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Free shipping $49+ on most items

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Financing
available here

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Discreet packaging

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Have a question?
716-217-0353

Description

Precision pH, now with a replaceable probe

The Bluelab pH PenPlus reads pH from 0.0 to 14.0 at 0.1 resolution and shows solution temperature in °C or °F on the same backlit screen. It carries an IP68 dustproof and waterproof rating, and its double-junction probe screws off the pen body, so years down the road you can refresh the probe instead of replacing the whole meter. It ships with pH 4.0, pH 7.0, and KCl storage solution so you can calibrate and start measuring the same day. Every pen is backed by a 2-year limited warranty on the meter and a 6-month warranty on the probe.

Replaceable probe 2-year limited warranty IP68 waterproof
Free shipping on orders over $49
30-day returns on all orders
Serving growers since 2006
Gallery
See it in action
Side by side
Cheap pH pens vs. the Bluelab pH PenPlus
Budget pH pens
  • Single-junction probes clog fast in nutrient solutions
  • Drift out of calibration within days
  • Probe wears out and the whole pen goes in the trash
  • No calibration reminder, so you forget and run on bad data
  • Dim, unlit screens that are hard to read in a grow room
  • Calibration solutions sold separately, adding $10+ on day one
Bluelab pH PenPlus
  • Double-junction probe resists contamination from nutrients
  • 2-point calibration (pH 4.0 and 7.0) holds accuracy to ±0.1 pH
  • Screw-cap replaceable probe: swap the probe, keep the pen
  • 30-day calibration reminder built into the firmware
  • IP68 dustproof and waterproof, built for daily reservoir use
  • pH 4.0, pH 7.0, and KCl storage solution included in the box
Key features
What makes this pen worth keeping

Double-junction pH probe ±0.1 pH

Two reference junctions instead of one. The outer junction takes the beating from nutrient salts so the inner junction stays clean, which means stable readings for longer before the probe wears out.

Replaceable pH/temperature probe

The probe unscrews from the pen body. When it eventually wears out, screw on a Bluelab pH ProbePlus, recalibrate, and you are back to fresh-probe performance in minutes without buying a whole new meter.

IP68 dustproof and waterproof

Rated IP68 for dust and water, so humid grow rooms, wet hands, and the occasional slip into the reservoir are all part of a normal day. It also reads solution temperature (0 to 50°C / 32 to 122°F) in your choice of °C or °F.

Backlit LCD with hold function

The screen lights up for reading in dim grow rooms. Press the hold button to lock the display so you can pull the pen out and read at eye level.

30-day calibration reminder

A built-in timer tracks the days since your last calibration and alerts you when it is time to recalibrate. No guessing, no forgetting.

Hydrating cap and auto-off

A KCl-filled silicone cap with an internal sponge keeps the glass bulb hydrated between readings, and an integrated lanyard keeps the cap attached. The pen switches itself off after inactivity to stretch its single AAA battery.

Specs
Technical details
pH Range
0.0 to 14.0 pH
Accuracy
±0.1 pH (at 25°C)
Temp Range
0 to 50°C / 32 to 122°F
Resolution
0.1 pH, 1°C / 1°F
Calibration
2-point (pH 7.0 and pH 4.0)
Power
1x AAA alkaline battery
Probe
Replaceable (Bluelab pH ProbePlus)
Warranty
2-year limited warranty on the pen; 6-month warranty on the pH/temperature probe (including pH ProbePlus replacements). Proof of purchase required.

How to set up and use your pH PenPlus

1

Hydrate the probe

Remove the storage cap and soak the probe tip in the included KCl storage solution for 24 hours before first use. This activates the glass membrane so it can read pH accurately.

2

Calibrate with two solutions

Dip the probe in the pH 7.0 sachet, press the calibration button, then repeat in the pH 4.0 sachet. A confirmation indicator on screen tells you the calibration succeeded.

3

Take your reading

Submerge the probe in your nutrient solution or reservoir and wait for the display to stabilize. The reading shows pH and temperature simultaneously on the backlit screen.

4

Rinse, store, repeat

After each use, rinse the probe tip in clean water, then replace the storage cap with a few drops of KCl solution inside. This keeps the probe hydrated and extends its working life.

In the box
Everything you need to calibrate and start measuring
Included with every pen
  • Bluelab pH PenPlus with replaceable pH/temperature probe
  • pH 7.0 calibration solution sachet
  • pH 4.0 calibration solution sachet
  • KCl probe storage solution
  • Integrated lanyard and silicone probe cap
  • Quick-start guide
Recommended add-ons
Not sure if you need the Conductivity Pen too? If you are hand-mixing nutrients, yes. pH tells you whether plants can access food, EC tells you how much food is there. Call us and we can walk you through it: 716-217-0353 / help@happyhydro.com
Questions
Frequently asked questions
The only setup is hydrating the probe in KCl solution for 24 hours (comes in the box), then doing a two-button calibration with the included pH 4.0 and 7.0 sachets. The pen shows a confirmation icon when calibration is successful, so you know you did it right. After that, you just dip and read.
This pen is designed for testing liquid solutions: reservoirs, runoff, tap water, or nutrient mixes. If you need to test directly in soil, coco, or other solid media, Bluelab makes a separate Soil pH Pen with a flat-tip probe designed for that. The pH PenPlus is the right choice if you are checking water or nutrient solution before you pour it.
Bluelab recommends calibrating once every 30 days, and the pen has a built-in reminder that tracks it for you. Each calibration takes about two minutes. You will eventually run out of the included sachets, so picking up a Bluelab Probe Care Kit or extra sachets is a good idea for the long run.
Yes, and that is the main reason to choose the PenPlus. The probe unscrews from the pen body and a new Bluelab pH ProbePlus screws on in its place; recalibrate and you are back in business. With proper care (rinsing after use, storing in KCl solution, recalibrating monthly), a probe typically gives 1 to 2 years of reliable use, and keeping a spare on hand means zero downtime when it is time to swap.
Yes. The probe tip is a glass membrane that must stay hydrated to read accurately. If the probe dries out, readings drift and eventually the probe fails permanently. Add a few drops of KCl solution inside the storage cap and keep it on the pen between uses. Never store the probe dry or in plain water.
The Bluelab pH PenPlus reads to 0.1 pH resolution with ±0.1 accuracy at 25°C. For hydroponic nutrient management, where your target range is typically 5.5 to 6.5, that level of precision is more than enough. Lab-grade meters read to 0.01 pH, but that extra decimal point rarely changes a grower's decision. One note: the PenPlus is built for nutrient solutions and needs a conductivity of at least 0.2 EC to read reliably, so very pure RO or distilled water on its own is outside its working range.
If you receive a defective or damaged unit, email us a photo at help@happyhydro.com and we'll make it right immediately: replacement or refund, your call. For change-of-mind returns, we accept returns within 30 days for items in new, resalable condition. If you're not sure whether this product is right for your setup, call us first at 716-217-0353. We'd rather answer your questions before you order.
Happy Hydro has been selling growing equipment since 2006. We've carried Bluelab for years because the systems work great and customers who buy them leave happy. Have questions before you order? Call 716-217-0353 or email help@happyhydro.com. We're easy to reach and happy to help!

Your Happy Hydro Shipping Experience

We ship fast from Buffalo, NY. Most orders ship within 24 hours, and typical delivery takes 3-5 business days. Shipping costs are calculated at checkout based on the products and destination, with free shipping available on eligible orders. Plus, plain-box packaging and real humans ready to help if anything goes sideways.

Fast fulfillment — most orders ship within 24 hours
Plain-box discreet packaging
Serving growers since 2006
What to expect
When you order from Happy Hydro

Fast Fulfillment

Most orders ship same or next business day from our Buffalo, NY warehouse via UPS Ground or USPS Ground Advantage. Expedited options are available at checkout.
* Shipping costs vary by product, order size, and destination
* Some products are excluded from standard free-shipping offers or ship separately from a vendor's warehouse

World-Class Customer Care

Our grower support team is here 10 am-4 pm EST, Monday-Friday. Call 716-217-0353 or email help@happyhydro.com.

Discreet & Secure Packaging

Every order ships in a plain brown box with no branding or logos. Your purchase stays 100% private. We can also ship to your local UPS Store on request.

Specs
Shipping details at a glance
Delivery time
3-5 business days
Default carrier
UPS Ground or USPS
Signature required
Orders over $500 only
Shipping cost
Calculated at checkout Rates depend on the products, order size, destination, and shipping service selected.
International
Canada only Email help@happyhydro.com your address & a screenshot of your cart for a quote
Returns
30 days on most orders Exceptions apply — orders over $400, multi-box shipments, and some vendor items may incur return shipping charges. Full policy
Questions
Frequently asked questions
Shipping
Check the order confirmation sent to your email or phone after checkout — it includes a tracking link. If you use the Shop App, you can track your order there too.
Most orders ship within 24 hours, and typical delivery takes 3-5 business days after shipment. Expedited options may be available at checkout depending on the products and destination.
Signature is only required on orders over $500. For added privacy, we can ship to your local UPS Store so you pick it up on your own schedule — just ask.
We default to UPS Ground or USPS Ground Advantage. Select an expedited option at checkout and we'll use the appropriate carrier for that service.
  • P.O. boxes: Yes, for small and lightweight items.
  • International: Canada only. Email help@happyhydro.com your address and a screenshot of your cart for a shipping quote.
  • APO/FPO: Not currently available.
For Canadian orders, import duties and taxes are the buyer's responsibility. You'll complete payment using your tracking number at UPS.com when your package arrives.
Title and risk of loss pass to you once we hand off to the carrier, but that doesn't mean we leave you hanging. Email help@happyhydro.com and we'll work overtime to track it down and make it right.
Payment
We accept credit/debit cards, PayPal, Coinbase, and Happy Hydro gift cards. Your card is charged immediately at checkout.
Double-check your billing address and card number. For larger purchases, your bank may have flagged it — a quick call to authorize the transaction usually sorts it out.
Promotions
Enter your code in the "Promo code" box at checkout and click Apply. One code per order, but you can combine a gift card with a promo code if you have both.
Subscribe to our mailing list for exclusive discounts and early access to sales. You can sign up at the bottom of any page on our site.
Returns & Cancellations
Email help@happyhydro.com within 30 days of delivery and we'll get you a refund or replacement, your choice. Items must be in original packaging with all parts in resalable condition. Multi-light orders, grow tents, orders over $500, and multi-box shipments may incur return shipping charges. AK, HI, and international buyers are responsible for return and warranty shipping. Some vendor-specific policies may apply — check the product page for details.
Refunds are processed through Shopify within 10 business days. Most customers see the credit back in about 5 days.
Reply to your order confirmation email or email help@happyhydro.com as soon as possible. Canceled orders may incur a processing fee depending on your payment method:
  • Credit/debit card: 2.9%
  • PayPal or Venmo: 3.5%
  • International PayPal: 4.0%
  • American Express: 4.1%
  • Shop Pay Installments / PayTomorrow: 6.5%
Support & Policies
Call or chat with our grower support team at 716-217-0353, Monday-Friday 10 am-4 pm EST. You can also email help@happyhydro.com any time and we'll get back to you quickly.
Your privacy matters to us. Read our full policy at happyhydro.com/pages/privacy-policy.
Why Happy Hydro

Why Buy From Happy Hydro

Happy Hydro began as a pipe dream in a garage and has grown into something built almost entirely on word of mouth and repeat customers. Rather than focusing on raising margins and obsessing over profits, we've always believed that the right combination of competitive prices, superior products, and world-class customer service speaks for itself. Our philosophy will never change: when you're happy, we're happy.

Our commitment
What you can expect from Happy Hydro

Real People, Real Growers

Our grower support team isn't a call center. They know the products because they're passionate about growing. Reach us Monday-Friday, 10 am-4 pm EST at 716-217-0353 or help@happyhydro.com, before you order or after.

Hand-Picked by Growers, for Growers

Every brand we carry was chosen by our founders because it performs. We only stock premium brands we believe in, and every item is inspected before it leaves our warehouse.

Fair Prices and Free Shipping

We work hard to keep our prices as low as manufacturers allow, and we include free shipping on orders over $49 so there are no surprises at checkout. Find a lower price anywhere and we'll match it.

Authorized for Every Brand We Carry

We're an authorized dealer for every manufacturer on our site. That means you get the full manufacturer's warranty on every purchase. No grey market, no expired stock.

30-Day Returns on Most Orders

Hard to commit to a product you haven't tried. Return most items within 30 days in original condition and we'll take care of it. Read the full policy.

Secure Shopping, Private Data

Every transaction is SSL encrypted. We don't store payment information and we will never sell your data to anyone, ever.

Volume and Commercial Pricing

If you're a commercial grower or putting together a large order, reach out before you buy. We have pricing available that we can't advertise publicly. Call 716-217-0353 or email help@happyhydro.com and we'll take care of you.

Questions? We're easy to reach.
Happy Hydro has been serving growers since 2006. Call or email our grower support team Monday-Friday, 10 am-4 pm EST, or email us anytime.

716-217-0353 help@happyhydro.com

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