Supplementing your COB Grow room with Led Strips

From around mid 2015, the COB(Chip on Board), specifically starting with the Cree CXB3590, revolutionised grower view’s of Led Lights as a real alternative to the ubiquitous HPS/CMH grow light. While the powerful incandescent HPS light’s still prevail for the devoted HPS grower, the success of the COB in changing minds about what LED lights could be has led to a proliferation in better performing led lights. The early promise and poor performance of the ‘Burple’ remains in the minds or many users, but has truly been supplanted by a wide range of better quality solutions.

The COB light has been used by literally thousands of users world wide and remains a staple tool for those wanting to find a HPS solution that delivers great PPFD at reduced heat and power levels. The intense beam and canopy penetration delivers great photonic flux, is relatively small in terms of form factor and is supported by a great array of secondary optics/reflectors, heatsinks and frames and while its cost remains relatively high the performance results by most all users is well documented.

The shift to more contemporary solutions has not seen it completely fall from favour, but there is little doubt the range of lighting products now available means the choice makes the COB solution only one of many. For those that have used a COB solution, are happy with it but would like a bit more, the following may make some sense if your considering an upgrade. Lets not throw baby out with the bathwater

Example of 4×4.

So a traditional 4×4 tent with COB’s might, as a minimum system have 9 x CXB3590, this would be around 450 watts( 50 watt per COB) and would be touted or used as a 1000 watt HPS replacement, 12x COB would likely be a better performer at 600 watts. Lets have a look at what 450 or 600 watt looks like in a 4×4 tent in terms of photonic flux and light distribution

So a 9 COB unit at 450 watts is an excellent Veg area, bordering on a good all purpose room. A simple upgrade would be to add 3 COBs to take it to a full 680 watt flower room and it would be a simple upgrade albeit requiring the re setting of the position of existing and new COBs.. What are the cons.

  • Efficacy of COBs’ is constrained by the chip density and consequent heat which mitigates optimum efficiency, COB builds are typically in the 1.9-2.1umoles/j range dependent on COB selections
  • Requires height to canopy consideration due to light intensity
  • the delta on min to max PPFD is constrained by the inherent beam/intensity in a COB design.

None of that is a deal breaker, but is there a better way

What if we keep our 9 COB basic build but we thoughtfully place a few modern strips in the build


If we add strips instead of COB’s, we lift the efficiency of the build over 2.2umoles/j, we get great min/max delta, so the corners are better photonically, it is more challenging in terms of build on the basis that strip mounting height will differ if using large pin fins on the COB. Apart from the actual assembly cost, the strip hardware is likely to be 2/3 the cost of COBS.

In summary both solutions work, the strip addition however lifts the total performance in terms of efficacy and coverage and can take a ‘vintage’ COB build and make it more contemporary rather than completely changing out a grow light, that has no doubt given you great service and good results for not a huge investment.

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