To get a another 1000w or just a 600?

I was talking to a friend and they said a 600w in a tent is almost just as efficient as a 1000 w compared to the electrical cost and such any help I already have 1 1000 but am gonna get more lights and would like an input

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Par per watt I believe just about all the 600’s I’ve looked at beat their bigger models. It’s still less light than 1000. But you’re doing more work per watt.

The real advantage to going to a 600 will be with multiple lights in a big area you can get as much or more out of 3 600’s than you can 2 1000’s. Plus you’re able to provide larger effective footprint and save a few hundred watts on your bill.


Thank you :slight_smile: so the efficiency is there noice

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This is quite large but something very important to have aroundCopy and paste it to your files for future reference


Estimated Cost Per Month
for Common Grow Room Items

Compare Grow Lights @ $0.25/kWh

Amounts are for if the lights are kept on for 18 hours a day for 30 days (540 hours).
In the flowering stage your lights will be on for only 12 hours/day so for those months
you’ll only need to calculate for 360 hours (12 hours x 30 days).

MH/HPS Grow Lights

150W - $20/month
250W - $34/month
400W - $54/month
600W -  $81/month
1000W - $135/month

LED Grow Light Examples

Advanced Platinum P150 - 87W - $12/month
Advanced Platinum P300 - 185W - $25/month
Advanced Platinum P450 - 255W - $35/month
Advanced Platinum P600 - 368W - $50/month

Note: Advanced Platinum is just one example of an LED brand that works well

for growing cannabis, but you feel free to check out more brands of LED grow
lights with true wattage plus yield estimates!)

LED grow lights use less electricity than CFL or fluorescent grow lights,
but will the savings in electricity make up for the cost?

Compare Various Fans @ $0.25/kWh

Amounts are for if the fans are kept on for 24 hours a day for 30 days (720 hours):

6" Clip-on fan - 13W - $3/month
10" tabletop fan - 35W - $7/month
4-Inch Exhaust Fan - 70W - $13/month
6-Inch Exhaust Fan - 125W - $23/month

Hydroponic Pumps and Accessories @ $0.25/kWh

Amounts are for if the pumps are kept on for 24 hours a day for 30 days (720 hours):

Air pump - 3W - $0.60/month
Water pump - 26.5W - $5/month
1/13HP Water Chiller - (Capable of lowering an average 20°F in a 30-Gallon tank) - 192W - $35/month

The air pump and water pump in your DWC system for growing marijuana contains a water pump and an air pump which both use electricity

Air Conditioner Examples @ $0.25/kWh

?Amounts are for if the ACs are kept on continuously for 12 hours a day for 30 days (360 hours) - hopefully you don’t have to keep your AC on this often or this long!

7,500 BTU Window Air Conditioner - 670W (for cooling, this unit also has a heating function that takes 1260W) - $61/month for cooling ($114/month for heating)
10,000 BTU Window Air Conditioner - 925W - $84/month
10,000 BTU Portable Air Conditioner - 1000W - $90/month
15,000 BTU Window Air Conditioner - 1330W - $120/month

Figuring Out Cost (Per Grow)

If it’s your first grow, when it comes to figuring out an estimated per-grow cost I recommend planning on it taking 5 months to get to harvest time (even though the average grow is usually about 3-4 months). Although you will hopefully get to harvest sooner, it’s better to estimate for too much money and have it cost less than the other way around!

Five months gives you plenty of time to mess up in the vegetative stage, use a long-flowering strain and still be ready for harvest. After you get some experience you’ll have a much better idea of how long it usually takes to get to harvest using your personal style and preferred strains. One other thing to remember is you’ll use less energy in the flowering stage because your lights will only be on 12 hours a day. You can figure that time out separately if you want, but I’m just going to pretend the lights are on 18/6 to make things simpler.

So now that you’ve begun to figure out your per-month prices, you can multiply them by 5 to get an estimate of how much a whole grow will cost you for each item!

As far as the cost of electricity when growing cannabis, how much money is actually going to come out of your wallet during the grow?

Example Setup ($0.25/kWh)
Remember to look up your local electricity cost because it’s probably much lower!

400W Grow Light - $54/month
2 x 6" Clip-on fans - 13W - $3/month x 2 = $6/month
10" tabletop fan - 35W - $7/month
6-Inch Exhaust Fan - 125W - $23/month

Monthly Electricity Cost: $90
Electricity Cost for 5 Months: $450

That’s a total of $90/month in electricity, so if you multiply that by 5 months you get $450 cost of electricity for the whole grow.

Once you’ve had a grow or two under your belt it’s a good idea to start looking at cost and reward to make sure you’re growing what you need for the price you want.

Let’s say you spend $450 on electricity in the grow, but produce 5 ounces of buds, that means you’re paying $90/ounce for electricity (plus the cost of setup and supplies). If that’s a good price for you then you can celebrate a good harvest, but if you’re not getting the right prices in your grow, it’s a good idea to evaluate and figure out what you need to change to get the results you’re looking for!

How do I determine my yields?
(What’s my limiting factor and how do I fix it?)

Learn how to figure out the cost of electricity for growing marijuana with a straightforward formula!For example, in the same previous grow I spent about $280 in electricity throughout the grow (if you add everything together). I harvested a little over 6 ounces which means I spent a little under $50/ounce in electricity. Considering it costs around $350 for a high-quality ounce in my area, that’s some pretty significant savings!

Another thing to consider when trying to estimate costs is how long a specific cannabis plant needs in the flowering stage before it’s ready to harvest. Some plants need up to 3 months in the flowering stage, so when determining cost it’s a good idea to factor in that extra time. Sometimes it’s worth it to pay more for better buds, but you should know that’s what you’re getting into!

Now that you’ve got a handle on figuring out your costs, let’s take a brief moment to talk a little bit about electrical safety.

Electrical Safety Tips

If for some reason your electrical equipment is in contact with water, don't touch it! You could get zapped!
Keep your grow area dry and quickly clean up any spills.
Keep everything as neat as possible. Try to put away anything that you don't actually need in the grow room.
Keep all electronics off the floor and make sure any wires are untangled and it's a great idea to tie them in place. A good rule of thumb is "electricity above the waist, water below the waist."
Use a surge protector. Many surge protectors are built with holes in the back so they can be mounted directly to a wall. Note: a surge protector offers protection for devices plugged into it; it doesn't protect humans (although a GFCI does)!

Get a stellar surge protector for your cannabis garden on!

Always have a smoke detector in your grow room. They're way too cheap to pass up!

Get a Ground Fault Circuit Interrupter(GFCI) - Many indoor grows involve having water somewhere near electrical outlets and a GFCI will protect you. A GFCI outlet stops power from flowing to the plug in the event of current-leakage (current-leakage equates to severe danger...electrocution!). You can also get outlets with GFCIs built-in for those who have experience in changing outlets.

Get an extension cord with a built-in GFCI on

Check your circuit breaker to make sure it can handle the amount of electricity you plan to use.

If you’re getting set up with a new grow room, or just getting started growing in a space for the first time, there’s a few things you need to do before you ever plug anything in! In addition to standard electrical safety precautions inside the grow room, you want to make sure your grow space can actually support the amount of power you need.

Once you know which plugs you’re going to use for your grow, you need to calculate how much energy your grow lights and fans will need (as explained in today’s article). Armed with that knowledge, you can make sure your outlets can support that much energy usage.

All electrical outlets in your house are on a circuit, and each electrical outlet in your grow room belongs to a circuit. Often the circuit breaker box has labels for which outlets in the house are on each circuit, but sometimes you need to figure it out yourself.

Once you know which circuits your plugs are on, the next step is to open your circuit breaker box and see what number is listed next to the circuit(s) you plan to use.

Check your circuit breaker box to see what Amps it can support, so you can figure out how many watts are safe to put on each circuit

Let’s say you’re using 120V outlets like most standard American outlets. If the circuit breaker is labeled for 15 Amps that means that circuit can handle 1800W worth of appliances (15A x 120V = 1800W). If it’s labeled with a 20 it means that the circuit can handle 2400 watts (20A x 120V = 2400W). For 30 Amps it’s 3600W.

If your appliances on a circuit combined equals more than those total watt numbers, you’re going to trip the circuit breaker at some point and everything on that circuit will shut off as a safety precaution.

Important: With all this in mind, it’s crucial to note that the limit of how much load a circuit can take is 20% lower for “continuous loads”. A “continuous load” is something that needs power for 3+ hours, so pretty much ALL of the power you will be using is a continuous load. This means you’ll want to split your power usage between circuits (not just outlets) when needed, and stay below the following wattages:

1444W on 15A circuit breakers
1920W on 20A circuit breakers
2880W on 30A circuit breakers

I have examples of different wattages listed in the main article, but consider that a 1000W light + 10,000 BTU air conditioner is already enough to go well beyond the 1444W safety limit if you have a 15A circuit breaker and even surpasses the 1800W maximum load limit!

Because of this we once had to power an AC with an extension cord that went to another room so it wasn’t using the same circuit as the lights and fans! Believe it not or, this is actually safer than putting extra load on an already overburdened circuit.

Take a look at this 30 Amps Circuit Breaker box on - why not get as good an electrical circuit as possible for your cannabis plants?

Use your common sense, if something just doesn't seem right, or if you have any second thoughts about safety you should listen to your conscience. It's better to be safe than sorry!

When it comes to electrical safety in the cannabis grow room, use your common sense! If something doesn’t look safe it probably isn’t!

Tips for Saving Electricity

It’s impossible to do all of these things at the same time, and sometimes you’ll have to choose between strategies, but this should help give you ideas on ways to possibly cut electricity use during your grow!


Keep your plant growing fast and healthy to potentially shave weeks off your grow. Every day you are powering your grow room adds to the amount of electricity you're going to use during the grow.
Choose a strain with a shorter flowering stage - there are strains that need as little as 8 weeks of the flowering stage before they're ready to harvest. Although there's nothing wrong with paying a little more to grow a longer-flowering strain! Some of the best strains need a little longer and it can be worth it to pay a little more.
Choose an auto-flowering strain - these strains will get you to harvest in about 3 months, sooner than any other strain.

Train your plant to grow flat under your grow lights to get the best yields. This will lower your amount of electricity needed for the same harvest!


Have your lights on during the cheapest time for electricity - Many electricity companies have certain times of the day that are cheaper than others when it comes to electricity, so if you have your lights on during those cheaper hours you will save!
Consider putting plant on 18/6 over 24/0 light schedule in the vegetative stage - that extra 6 hours a day without your light on can make a big difference on your electricity bill each month, and your plant will still grow healthy and fast with 18 hours of light!
Choose a more efficient grow light - growers using fluorescent lighting might consider switching to a more efficient light. For example, if you're using CFLs, you'll get almost twice as much yields per watt by switching to an equal wattage HPS. So if you had 150W worth of CFLs, you could about double your yields by switching to a 150W HPS (without changing anything else). Learn more about upgrading your grow lights for better yields/watt.
Cannabis plants growing under LED grow lights - will LEDs save you money in the long run because they use less electricity?Get the smallest grow light you need to produce your result -  If you're already growing more bud than you need, you might consider moving down in grow light size. If you're using HPS grow lights, consider that a 600W HPS is more efficient than a 1000W HPS (600W HPS is actually the most efficient in lumens/watt of all HID grow lights), so if you could get enough bud from the 600W HPS you'd be getting more light per watt, and therefore more yield/watt. Why aren't my yields bigger with the light I have now?
Lower the power of your light initially, (or start with fluorescents) until plant gets big enough to need more light. Some grow lights allow you to reduce their power output to 80% or 60%. If you have a seedling that's just a few inches tall, it doesn't need a big light and you can reduce your power without slowing growth down at all, but you'll be using far less electricity. Same thing with fluorescents; even if they're not the most efficient lights for producing buds, they are very low power and work perfectly for growing seedlings.
Keep lights the right distance away - Keeping lights too far away from your plant will prevent them from getting all the light they can for the wattage used.
Fill space under light using plant training so you're using as much light as possible to increase yields. You want your entire grow space under the light filled with a flat canopy of buds for the best results indoors under grow lights.
Consider training techniques with less down time. For example, more advanced training techniques such as manifolding can add 2-3 weeks onto your grow, while something more simple like FIMing may take a little more physical work on your part in the long run to manage your colas, but it won't add much if any time to your grow so you'll end up saving on electricity.

Using a less powerful grow light while your plants are young will save electricity!

Use a less powerful grow light for young cannabis plants to save electricity

Manage Temperature / Air

Smart fan placement - place your fans where they will be most effective so you don't need as many of them running at the same time
Straight-line exhaust - Keep your exhaust as straight and short as possible. Bends in the ducting, and long distances for the air to travel will make your exhaust system much less effective. If at all possible try to aim for an efficient exhaust system over an air conditioner! AC's often use as much as, if not more electricity than your grow lights. Although you can't keep your tent cooler than the air in your room, there's a lot you can do to help even the temperatures out before you have to invest in an AC! Even with an AC, it's a good idea to minimize how often you turn it on.
Use time of day and fan speed to help manage temperature. For example, if it's hot during the day you might consider putting your lights on at night when it's cooler so you don't need to turn on the AC. 
Grow at temperate parts of the year if possible so you don't need an AC and can keep your lights on during the parts of the day when it's cheapest instead of when it's warmest.
No fans until they're needed - Chances are you don't need any fans in the beginning of your plant's life. As long as it's not very muggy, seedlings and young clones should be just fine without a breeze until they get a little older and actually start getting bushy.
Learn more about how to control temperature in the grow room!

For your exhaust system, try as best you can to keep ducting in as straight (and short) a line as possible - this makes it much more efficient at removing heat!

One way to keep the heat down (and not need to spend electricity on an AC) when growing cannabis is to have an efficient exhaust - that means making as short and straight a line as possible from the light to the outside!

I hope that helps get you started with figuring out the cost of electricity and setting up your grow room so you spend as little as possible while producing the results you want! Let us know if we` anything!