Current Culture Under Current Pro Evolution 12

Current Culture Under Current Pro Evolution 12


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Current Culture High Performance Deep Water Culture - The Proven Production System

The Under Current® features the patented Sub-Current Culture® circulation method. This high-performance water culture system is unmatched in efficiency, layout versatility and ease of use. The Under Current® utilizes negative water pressure to recirculate oxygenated nutrient solution through the plant’s root zone ensuring pH and EC levels are uniform throughout the entire system.

The Under Current® is the cornerstone of the CCH2O Proven Production Approach when used with Cultured Solutions® Nutrients and the CCH2O Nutrient Dosing System.

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NEW 2019 UC PRO Upgrades: Add Back Kit & Air-Flow Regulator

The Add Back Kit provides a simple approach to adding concentrated fertilizers or pH adjustors directly into your Under Current® system. It utilizes a patented Mazzei injector to pull concentrates directly into the system’s solution. The Add Back Kit uses the Under Current® system’s existing water pump and flow to naturally draw nutrient into the system via venturi action. Safe and simple.

The Air Flow Regulator is an effective tool for easily calibrating air flow into and through the aeration distribution system. This allows growers to target specific aeration rates to ensure proper aeration levels are maintained throughout the growing cycle. The Air Flow Regulator is especially useful in situations where multiple Under Current® systems are supplied from one central air pump or bank of air pumps working in unison.

What is the Under Current® PRO?

The Under Current® PRO is a Greenhouse Grade Re-Circulating Water Culture System made specifically for Commercial Growers.

The re-designed Under Current® PRO represents the largest, highest quality, most durable version of our Under Current® system to-date. With high levels of aeration and circulation, nutrient efficiency is maximized and yields are expected to be off the charts.

The 35 gallon Under Current® PRO systems will function much like their 8 and 13 gallon counterparts but will feature several unique and up-sized heavy duty components. Every element of the system has been reinforced and maximized for longevity in adverse greenhouse-style conditions.

Growing in the Under Current® PRO

For commercial applications the Under Current® PRO triumphs in efficiency and yields. The PRO system offers growers the opportunity to fill very large spaces and grow massive plants without the extra work of managing multiple systems and reservoirs. Having fewer larger systems equals higher productivity in terms of workflow, transplanting, maintenance and harvesting.

The Under Current® PRO system would be best situated in either a greenhouse or indoors with a combination of vertical and horizontal lighting. The 35 gallon PRO growth module with single plant sites will be best utilized on 70”+ plant centers. Starting plants in our 8-gallon Under Current® systems and transplanting them to the PRO module at a height of 3-4’ will yield a monstrous 8-10’+ finished plant when harvested.

For even more flexibility we offer interchangeable PRO Lids in 4, 6 and 8-site configurations. These durable ABS lids increase the PRO system’s versatility and allow for tighter plant spacing, quicker turnaround times and Sea of Green (S.O.G) style cultivation methods.

All Under Current PRO Systems Include:

  • PRO Growth Modules 35 gallon
  • Choice of Growth Module Lids
  • 3” Manifold Fittings
  • 3” UC Spin-Tight Bulkheads
  • Drain Valve
  • Air Flow Regulator-XL
  • Premium Mag-Drive Return Pump
  • Premium Linear Air Pump(s)
  • Aqua-Pore Pro XL Air Diffusers
  • PRO Air Distribution Manifold
  • Quick Connect Air Hose
  • In-Line Filter(s)
  • Add Back Kit
  • Float Valve w/ Reservoir Adapter
  • Chiller Adapter
  • Garden Hose Drain Adapter
  • Cultured Solutions VEG A/B
  • 1-Year Warranty.

NOTE: 3" PVC or ABS Pipe, 1.5" PVC or ABS Pipe, amd Multi-Purpose PVC/ABS Pipe Glue will need to be purchased before you can assemble your UC Pro System.

Benefits of Growing in an Under Current®

Grow Trees

Yield more with less. Reduce plant counts. More production per plant.

Get Your Weight

Accelerated growth rates. Cut veg times. Heavy Yields = Heavy Profits.

Take A Vacation

Easy and reliable. No timers, no guesswork. Reduced labor and maintenance.

RDWC Hydroponics Growers Guide

Want to learn to grow like a pro in the Under Current® system? Take a look at our Current Culture™ Grower's Guide for step by step instructions and tips.

Required Accessories:

These important tools will maximize your garden's production. Suggested products listed as add-ons at top of product page above.

RO Water Filter:

Water quality is of the utmost importance when growing in water culture. RO water allows growers to control all minerals and nutrients their plant's uptake. A reverse osmosis water filter is recommended for source waters exceeding 100 ppm.

Water Chiller:

The highest levels of dissolved oxygen are only accessible with cool root zone temperatures. High water temperatures limit the solutions ability to hold dissolved oxygen, while also providing the ideal environment for dangerous pathogens. Water chillers ensure cool, consistent solution temperatures are provided to the root zone.


Utilizing metering equipment in your garden will offer precise monitoring over essential environmental factors such as pH, ppm/EC, temperature and humidity. When used in conjunction with dosing and controlling equipment, the Under Current has the potential to be completely automated.

Top-off Reservoir:

Using a top-off reservoir will maintain accurate and essential solution levels throughout the course of the growing cycle, ensuring plants stay hydrated.

Under Current® System Options

Have questions? Please give us a call and one of our knowledgeable tech specialists will be ready and able to answer them all!


Current Culture Under Current Pro Evolution 12 Videos

Product Q&A

Current Culture Under Current Pro Evolution 12 Questions & Answers

General Recommendations

What are the most common mistakes made in water culture?
a. Running nutrient strength too high. This can inhibit water uptake and contribute to metabolic stagnation and subsequent plant stress.
b. Using incompatible inputs in solution causing convolution of the water chemistry. Avoiding organic, low solubility inputs is strongly recommended.
c. Micromanaging pH. Adjusting pH too frequently can lead to nutrient solution instability and issues.

What makes the Under Current a more efficient hydroponic method?
Less frequent nutrient change outs, lower nutrient usage rates, less pH fluctuations (less pH adjusters needed) and the conservation of precious H2O.

What makes the Under Current more productive compared to other hydroponic systems?
When a water culture system is operated properly, plants benefit from an increased uptake of water and minerals in solution as well as sustained cell turgidity. Given the favorable CEC of water, a plants nutrient uptake efficiency in water culture is very high, resulting in superior results.

Planning And Sizing

What is the approximate volume of solution in each module during standard operation?
a. 8 gallon – approx. 6 gallons
b. 13 gallon – approx. 10 gallons
c. 35 gallon – approx. 30 gallons

How do I calculate my total system volume?
a. Multiple total number of modules plus 1 (for Epicenter) multiplied by the approximate volume per module. Take this volume and add 10% to account for solution in joints and manifolds.
b. Example: UCDB16XL –
i. 17 x 6 gallons per module = 102 gallons
ii. 102 + 10% = 112 gallons

Can I integrate a nutrient auto dosing system?

What is a top-off reservoir and why do I need one?
A top-off reservoir is used to maintain consistent system volume and water chemistry. The top-off reservoir will supply solution via gravity to the float valve in Epicenter (control module).

Do I need a water chiller?

Do I need a Bulkhead Filter for each growth module?

Is there an option for custom system spacing?
Yes, all systems are available in a “Boneless” configuration without straight sections of pipe, allowing you to customize your plant centers.

Does a "Boneless" system include instructions on how to cut/couple pipe?
Yes, each “Boneless” kit includes a Boneless cut chart and recommendations for gluing and assembly.

Operating the Under Current

Should the Air Pump and Water Pump run 24/7?

Where should I set my solution level?
a. Initial Transplant: See diagram.
b. Veg: 2” above base of net pot.
c. Bloom: 1” below base of net pot

What should be in my top-off reservoir?
When operated properly, top off should be balanced the same or slightly higher as the solution in the system.

Does a top-off reservoir help maintain water chemistry (pH/EC) stability?
Yes. Any fluctuations in pH/EC can have a negative effect on plant health.

How do I adjust pH?
a. CAUTION: Do NOT add pH concentrate directly to Epicenter (control module).
b. If the pH is between 5.5-6.5 no adjustment is necessary.
c. Dilute pH adjuster 1:128 (about 1 oz. adjuster per gallon of fresh water). Once diluted slowly add to the system, allow 20-30 minutes for mixing. Re-test once pH has stabilized, add more diluted adjuster as necessary.

What solution temperatures are optimal?
We recommend maintaining a water temperature between 65-68 degrees F.

What solution temperatures are optimal?
We recommend maintaining a water temperature between 65-68 degrees F.

Do I need to include the initial PPM of my source-water when calculating nutrient levels?
Yes. Adjust accordingly.

Do I need to include the initial PPM of my source-water when calculating nutrient levels?
Yes. Adjust accordingly.

Do I have to empty out the entire system to do a nutrient change-out?

What do I use to clean the system? Mix Ratio of Cleaning Agent?
Physan 20, follow manufacturer’s directions.

Growing in the Under Current

How do you veg for the system?
a. Under Current system (8 gallons): Bare root or cube (rock wool, oasis, etc) propagated plants can be placed directly into our CCH2O Net Pot and placed directly into a Under Current system for optimum growth. This technique is perfect if subsequently transplanting into a larger Under Current system (13 gallon or 35 gallon PRO) at a wider plant spacing.
i. In this case, the entire CCH2O Lid (with Net Pot) can be picked up and moved directly to another Under Current growth module for flowering. This method is ideal for avoiding unnecessary root damage during transplant into bloom.
b. Ebb and Flow table (Periodic Flood): Bare root or cube (rock wool, oasis, etc) propagated plants can be placed directly into our CCH2O Net Pot or 4″/6″ rock wool cubes and placed in a typical tray. Some natural root pruning may occur as the roots grow through the net pot due to the intermittent watering cycle.
c. Ebb and Flow Table (Continuous Flood): Bare root or cube (rock wool, oasis, etc) propagated plants can be placed directly into our CCH2O Net Pot or 4″/6″ rock wool cubes and placed in a typical tray. Adding air diffuser to the tray will create a water culture environment. This will stimulate root growth similar to the Under Current system and prepare the plants for a fairly seamless transition.
d. Drip: Bare root or cube (rock wool, oasis, etc) propagated plants can be placed directly into our CCH2O Net Pot or 4″/6″ rock wool cubes. A drip system with emitters in each net pot/cube can be placed on a bench or in a flood tray. Some natural root pruning may occur as the roots grow through the RW cube.

What grow mediums are recommended for use in the Under Current?
a. Any non-wicking inert grow media tends to work best. Expanded clay pellets and growstones are some of the most popular.
b. When using a wicking media like rockwool be sure to adjust solution level to ¼” below contact with the R.W.

Nutrient Considerations

What is the best nutrient for the Under Current?
Pure mineral-salt based nutrients like Current Culture’s Cultured Solutions are the most compatible with actively aerated water culture.

What is the recommended nutrient strength for the Under Current?
a. Veg: 100-400 ppm / 0.2-0.8 EC
b. Bloom: 450-900 ppm / 0.9-1.3 EC
c. **Based on ppm 500 scale

Are carbohydrates/sweeteners, enzymes and beneficial bacteria recommended in the Under Current?
No. These tend to create bio-films and de-stabilize water chemistry.

Should I use Ca/Mg in the Under Current?
When using Reverse Osmosis (RO) or De-Ionized (DI) water Calcium Magnesium is recommended at 0.25-1mL per gallon. The Cultured Solution’s Coco Cal Supplement is your best choice.

Should I change my nutrient strength each week?
Follow manufacture’s nutrient schedule as recommended.

How frequently should I change my nutrients?
Change outs are recommended every 7 to 14 days, or if pH becomes de-stabilized (drifts more than 0.3 per day).

Do I need to flush my system between change-outs?
No, assuming only compatible inputs are being used a simple drain and refill is sufficient.

Is it possible to over-aerate my Under Current?
Yes, we recommend aeration levels stay between 0.75-1.5 liters per minute/per gallon. Exceeding these levels may cause mineral precipitation and nutrient de-stabilization.


What should I do if I make a mistake?
Observations and slight adjustments are the best way to dial your system in when in doubt give us or CCH2O a call.

Tech Specs

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