Algae Scrubber Advanced

Floyd R Turbo said:
You can run parallel strings using a CC driver with say 1.5A output, and put a fuse on each string. Match the strings for Vf, and you have a current divider. If one LED blows and you lose a string, the other string will get 1.5A for just long enough for the fuse to blow, saving that whole string.
Click to expand...

Thanks again Floyd! I know you recommended series earlier and with your great explanations it's pretty clear that I should go in that route. Furthermore, it seems simple and we have an ohm meter to test each LED in case one goes out.

Here are the specs on the LEDs:

"¢ Forward Voltage: 2.2-2.6V
"¢ Forward Current: 750mA

Will this CV Mean Well LPV-60-48 60W 48V 1.25A work for a series circuit? I can get a higher amperage one if needed. Link to the item in case you need it.

http://www.ebay.com/itm/Mean-Well-L...558630?hash=item2a3ccaee26:g:E5wAAOxyIPNTcYKl
 
So, I should use two LPC-35-700 or three LPC-20-700? What I'm gathering is run a series with a driver at 700mA. I won't have to worry about a crappy driver starting a fire and I can run few LEDs than the max output and still get the same result.
 
An ohmmeter won't necessarily tell you that an LED is bad. You need a battery tester for that, just 2x 1.5V AA's, if the LED lights up, it's good (Rapid and Steve's carry these for like $1)

the LPV-60-48 will work for 2 parallel strings, each running at approximately 625 mA which is a good current for more DR LEDs, but not for a single series string.
 
Jade5051 said:
So, I should use two LPC-35-700 or three LPC-20-700? What I'm gathering is run a series with a driver at 700mA. I won't have to worry about a crappy driver starting a fire and I can run few LEDs than the max output and still get the same result.
Click to expand...

Sorry I missed this reply. LPC-35-700 says it can handle up to 48V drop at 700mA, 48*0.7 = 33.6W rated power. These are good drivers so you can push them, but it's always better to let them run a bit lower than rated power, heat is the enemy so they will last longer

For 18 3W Deep Reds, you have 18 * 2.2 = 39.6V or 18 * 2.4 = 43.2V so either way you are under the "rating" of 48V, and at 700mA you would have wattage output of 27.72 and 30.24, so technically you could use one LPC-35-700 and worst case (2.4v Vf per LED) you would be running at 90% of rated load. If you used two, each would be running at 45% rated load
 
Floyd R Turbo said:
An ohmmeter won't necessarily tell you that an LED is bad. You need a battery tester for that, just 2x 1.5V AA's, if the LED lights up, it's good (Rapid and Steve's carry these for like $1)

the LPV-60-48 will work for 2 parallel strings, each running at approximately 625 mA which is a good current for more DR LEDs, but not for a single series string.
Click to expand...

Thanks for the source!

Ok I pretty sure I'm understanding this correctly.

I could use this LPV-60-24 24V 2.5A 60W and run 3 parallel strings each running at about 833mA or is this too much?

I could use this LPV-60-15 15V 4A 60W and run 6 parallel strings each running at about 666mA?
 
The issue is that a CV device is not really a "driver" but is more like a power supply. Usually you use a CV source to power something that has a PWM chip on it or something. The power supply is not a driver, it is powering a driver (which requires a CV source)

A CC device is a driver and can be connected to an LED array directly. It's sort of like a power supply and driver combo, or simplicity's sake.

A string of LED will have a range under which they operate, and that means Vf will vary dependent on the current and the junction temperature. So Vf is hard to "force" or rather if you try to force it, the current will vary and if you are forcing a voltage, some LEDs will want one current, some will want another, and then you have components fighting each other and the result is heat or operating outside of their normal parameters.

If I got that all wrong, someone please feel free to correct me with the "you're wrong dumba--" stick.

But the key is that if you are going to use a CV power supply, you have to have the exact voltage on the load side that matches the power supply voltage. Meaning, you can't do 6 strings of 3 or 3 strings of 6, because your Vf does not equal 24V. Your Vf of your strings has to equal 24V.
 
Vf for each LED is inherent to the LED. If you try to force a Vf that is higher than what the LED is designed for, boom.

current, on the other hand, is what the LEDs were designed to operate under, in a range. So a I(max) of 700mA means you can run that LED at 0-700mA and it's Vf will vary based on the current being pushed through it (and it will vary a bit based on junction temp heat as well)

If you go the other way and force Vf, the current will vary based on the LED characteristics and the junction temperature. But the problem is that LEDs are not designed to be ran under CV, so you can have some really bad things happen. For instance, if an LED will operate with a Vf of 2.3V and it will hold that pretty steadily for an input current of 400-650mA, what will the amperage be if you supply 2.3V constant? The answer is, you don't really know. It could try to draw 400mA or 650mA and you can't really control that, not with a basic power supply.

So I would just focus on CC drivers. Much simpler
 
Floyd R Turbo said:
Vf for each LED is inherent to the LED. If you try to force a Vf that is higher than what the LED is designed for, boom.

current, on the other hand, is what the LEDs were designed to operate under, in a range. So a I(max) of 700mA means you can run that LED at 0-700mA and it's Vf will vary based on the current being pushed through it (and it will vary a bit based on junction temp heat as well)

If you go the other way and force Vf, the current will vary based on the LED characteristics and the junction temperature. But the problem is that LEDs are not designed to be ran under CV, so you can have some really bad things happen. For instance, if an LED will operate with a Vf of 2.3V and it will hold that pretty steadily for an input current of 400-650mA, what will the amperage be if you supply 2.3V constant? The answer is, you don't really know. It could try to draw 400mA or 650mA and you can't really control that, not with a basic power supply.

So I would just focus on CC drivers. Much simpler
Click to expand...

Thanks for the great explanation! You've really cleared up a lot of confusion for me! I've spent far too long looking at this by myself. I'm glad you are willing to help! Keep up the good work boss! Much appreciated!
 
@Floyd

I know you recommend running blues at half power, dimmed or diffused. I was going to run my blues in series. I noticed that the blue Vf (DC 3.0-3.4V, 700mA/1W) is different than the red Vf (DC 2.2-2.6V, 750mA).

However, it's my understanding that since the Vf of the red in front of the blue is lower the blue will have the same Vf as the red or slightly lower due to inefficiencies. Essentially the blue will not burn at 100% because it is in series with reds that have a slightly lower Vf. Is this correct or do I need a completely different driver for the 3 blue LEDs?
 
In a series string with a CC driver, the Vf will be whatever it is at that current. So your reds will drop 2.2V and your blues will drop 3.0V, etc. It doesn't matter.

Are your blues 1W and reds 3W? If so, just put them in series. The 1W blues will have a lower radiometric flux output than a 3W blue, so that's actually good - it simplifies the build. You won't have to do anything funky like putting a pair of blues in parallel within the series string (current divider)
 
Floyd R Turbo said:
In a series string with a CC driver, the Vf will be whatever it is at that current. So your reds will drop 2.2V and your blues will drop 3.0V, etc. It doesn't matter.

Are your blues 1W and reds 3W? If so, just put them in series. The 1W blues will have a lower radiometric flux output than a 3W blue, so that's actually good - it simplifies the build. You won't have to do anything funky like putting a pair of blues in parallel within the series string (current divider)
Click to expand...

The blues I ordered were 3W do you think that is going to be a problem? Should I cancel it and order 1W blues? Maybe I should just make something to diffuse the 3W blues?
 
karimwassef said:
with a really good scrubber, can you avoid using RODI water and just go tap water in?
Click to expand...
Be careful. It will all depend on what's in that tap. Either way I would treat with prime. Some people can use tap for decades without much issue. Some people, like me, 1TDS can be deadly. Then there's everything in-between.

Then there's periodic maintenance the municipality will perform that could be damaging to your tank but not you so they won't notify out. And then there's possible changes in how they treat. Then there's Flint Michigan.
 
This is a controlled experiemnt. LED growth vs CFL.

Well, I pulled the trigger and bought 2 x 30 W Grow Light LEDs.
** The lights I got were NOT plug and play! I kind of expected that however when I read that somewhere.
*Luckily- I save things that I think might be usefull on another project in the future!
I had several 5ft 3 prong/wire plug and wire I cut off my old/used PC lights.
So I got out my soldering iron and solder- that gets used once every 5 yrs or so, and soldered and taped the wires up- now like new!- freebie too.

Here are the lights- I bought two of them- shipped to me for less than $40 total.


After installing the wire/plug. Did NOT require any type of ballast/transformer, etc.


I used my noodle and devised a free, easy way to hang the lights at the existing area using some old (saved for future projects) fiberglass rod sections from an old tent I once had.
I used some old high tensile line salvaged out of my sailing gear. Todd_Sails- right?

The experiment is one sheet has CFL's and one has LED's.
I cleaned both sheets equally and at the same time this time so they both start even.







I'm also tried Aluminum Foil for the top splash guard this time, instead of clear plastic.
The alum. foil kinda stays creased around the pipe better than plastic wrap, and it will block the light too.

You can be sure I'll post back with the results,
Todd
 
Watch the screen with the LEDs on it for signs of photosaturation. The intensity of LEDs is much more than CFLs at the same distance. May need to split up photoperiod or reduce it.

Todd...sails?
 
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