Use of Lasers in Controlling Pest Algae and Corals

[discotu]

great thread...very informative. Quick question, what is the effective burn range of these lasers? It appears that focusing is require to get the maximum burn...and assume as the beam gets longer so does the divergence(out of focus). I understand it'l be different depending on the "target"....im sure you can burn a retina at greater distances than skin on someones arm. Just curious.

[CalmSeasQuest]

You're right discotu - The focus and optics are critical. If the beam end-point isn't focused to nearly that of a pin-head, the laser has little burning effect (although it is no doubt still very dangerous to your eyesight and that of anyone else within sight of the laser.) My tanks are small, so my working distances are less than most, but I've had no problem eradicating pests ~24" from the laser.

My laser, (like most higher power lasers) is focusable. The focus has to be manually adjusted based on the distance to the target. I also upgraded the optics (G-1.) It is supposed to provide an increase in efficiency/power output - although I don't have a LPM to verify.

My waterproof 1.2mW 445nm should be arriving soon. As the the waterproof hosts are fixed-focus, I'm curious to see how it will impact function.

[Wrench]

My tank is 36" deep and I have a problem zapping the buggers that are towards the back of the tank. I suppose quite a bit of energy is being lost as it passes through that much water.

Are you guys having luck killing mojano's with these things? After a few weeks I'm noticing that some of the buggers that I've zapped come back in a few days.

[Wrench]

My tank is 36" deep and I have a problem zapping the buggers that are towards the back of the tank. I suppose quite a bit of energy is being lost as it passes through that much water.

Are you guys having luck killing mojano's with these things? After a few weeks I'm noticing that some of the buggers that I've zapped come back in a few days.

[JasonD]

I can say from experience that Aptasia are no match for these high power lasers, it's almost unfair

[CalmSeasQuest]

Originally Posted by Wrench

My tank is 36" deep and I have a problem zapping the buggers that are towards the back of the tank. I suppose quite a bit of energy is being lost as it passes through that much water.

Are you guys having luck killing mojano's with these things? After a few weeks I'm noticing that some of the buggers that I've zapped come back in a few days.

Originally Posted by JasonD

I can say from experience that Aptasia are no match for these high power lasers, it's almost unfair

I didn't have any Mojano in my tank to test, but my success rate with Aiptasia appears thus far a perfect 100%.

Xenia on the other hand are proving incredibly resilient. I have a colony that I've been targeting to maintain the existing borders. While the laser is "eventually" effective, I've finding that it might take as many as 4 sessions (done daily) to finally kill the larger polyps.

Even so, spending a few minutes lasing through the glass over the course of a few days is still easier than most other options.

[TheFishMan65]

I think mojanos maybe harder. I have been using a 1 watt and find it takes quite awhile.
CSQ - want me to send you some

[CalmSeasQuest]

Originally Posted by TheFishMan65

I think mojanos maybe harder. I have been using a 1 watt and find it takes quite awhile.
CSQ - want me to send you some

LOL - Thanks TFM, but I think I'll pass on your generous offer. Since I started this thread, I've had MANY invitations from local reefers to "test" the process on Aiptasia and Mojanos in their tanks.

Apparently there is no shortage of these pests.

[CalmSeasQuest]

I finally received the waterproof 1.2W 445nm ordered from Lazerer (Ordered 12/15/11, shipping notice 12/21/11, received 1/11/12.)

I haven't had time to do much with it yet - It came in on-spec (per the power certificate.) I've got it soaking in saltwater to remove any oils left over from manufacture and to make sure it's absolutely waterproof before submerging it in my tank.

I did briefly test it underwater, and at first glance I am not impressed. It seems it will be very difficult to maintain a tight enough focus for optimal use as a burning tool. I will withhold judgement until I can do some actual in-tank testing, but based on what I'm seeing, I suspect that working from outside the tank with the 1.8mW 445nm will be far more effective.

[Genj]

CSQ, I've been following this thread and the older now seemingly inactive thread for some time now. Noted all safety concerns and I feel that moving forward is something that I would like to do.

That being said I have two questions;

1) have you noticed any impacts to the livestock and their vision?
2) assuming a $250-300 budget, do you have any personal recommendations on the brand, type, wattage of laser to accommodate a tank with a front to back depth of 22"?

Thank you!

[CalmSeasQuest]

Originally Posted by Genj

CSQ, I've been following this thread and the older now seemingly inactive thread for some time now. Noted all safety concerns and I feel that moving forward is something that I would like to do.

That being said I have two questions;

1) have you noticed any impacts to the livestock and their vision?
2) assuming a $250-300 budget, do you have any personal recommendations on the brand, type, wattage of laser to accommodate a tank with a front to back depth of 22"?

Thank you!

While others have and reported no ill effects (at least thus far), I don't use the laser when any fish are in eyesight of the beam endpoint. The tanks I'm using for testing include a frag tank with no livestock, and a small DT that has only a few fish. A pair of clowns that rarely leave their host, and a Mandarin who is usually in the aquascape hunting. I would not recommend using a laser in a heavily populated tank without taking precautions to protect the livestock from being exposed to the beam endpoint (and of course crossing the beam.)

I am told by those far more familiar with lasers than myself, that repeated, unprotected exposure to the beam endpoint will damage the vision of the livestock. I believe this to be true, especially when you consider the tank's inhabitants could be just a few inches away.

The jury is still out on my latest purchase (Lazerer 1.2W 445nm) which would fall in your stated price range. For our purpose, I believe higher power output is important, especially at further distances/depths. I am very pleased with and would recommend the 1.8W Survival Laser, but it is higher in cost. I would suggest reading through LaserPointerForums.com - There are many very knowledgeable laser hobbyists and professionals, many of which build and sell high power units that can be purchased at lower costs than through commercial vendors.

I still beleive 405nm is a better wavelength for our purpose as it can be focused to a tighter point, but there aren't many higher power 405nm options available yet.

Whichever option you choose - remember to purchase the appropriate eye protection.

[rwb500]

Originally Posted by CalmSeasQuest

I still beleive 405nm is a better wavelength for our purpose as it can be focused to a tighter point, but there aren't many higher power 405nm options available yet.

does that difference in wavelength really have an effect for this application? i dont think the scale of this application is small enough to require worrying about the wavelength.

[CalmSeasQuest]

Originally Posted by rwb500

does that difference in wavelength really have an effect for this application? i dont think the scale of this application is small enough to require worrying about the wavelength.

I'm not sure if I understand your statement. It's not the spectrum, but rather the ability to obtain a finer focus that makes the difference. The 445nm emitters create a bar-shaped beam end point (rather than a pinpoint.) Whereas the 405nm focuses to a much finer pinpoint. This allows for more laser energy to be directed at a much smaller area. Simply said, it burns much better.

This allows you to use a comparatively lower output laser and achieve the same or better results.

[rwb500]

oh i thought you were referring to the theoretical ability of a shorter-wavelength source to be focused into a narrower beam. such as blu-ray vs dvd (blue laser can focus on finer details in the disc than red laser).

i was obviously missing your point, sorry. just trying to help.

[CalmSeasQuest]

Originally Posted by rwb500

oh i thought you were referring to the theoretical ability of a shorter-wavelength source to be focused into a narrower beam. such as blu-ray vs dvd (blue laser can focus on finer details in the disc than red laser).

i was obviously missing your point, sorry. just trying to help.

No problem, you're right about Blue Ray, in fact they use 405nm for the same reason.

[Mrs. Music]

This just seems a wee too overkill for me...maybe I am just a simple person. Granted we do this crazy thing anyway...putting salt water in a box, throw in a few electrical appliances. And we survive it. you put a laser into the mix and someone is gonna shoot their eye out. laser their eye out I mean. boys and their toys...jk guys.

[salty joe]

Originally Posted by CalmSeasQuest

The OD4 acrylic (the most expensive square foot of .140" thick plastic I've ever purchased) should arrive next week so I can start working on the endpoint shield. While I'm looking forward to testing the underwater host, I'm finding extremely easy to work through the glass.

Are you using the endpoint shield? Can you elaborate?

Do you place the laser directly on the glass and then focus?

Is it possible for the beam to reflect from the inside surface of the glass?

Do you think the 405 would work on the back of a 45" tank?

I agree, give these things all the respect of a loaded gun.

[CalmSeasQuest]

Originally Posted by salty joe

1) Are you using the endpoint shield? Can you elaborate?

2) Do you place the laser directly on the glass and then focus?

3) Is it possible for the beam to reflect from the inside surface of the glass?

4) Do you think the 405 would work on the back of a 45" tank?

5) I agree, give these things all the respect of a loaded gun.

1) I've tried a couple of different options (detailed earlier in this thread.) I'm still waiting on the delivery of some OD4 material for fabricating a conical shield that can be attached to a acrylic rod. In my case, it's not critical earlier in the thread, I have very few fish in my DT and none in my FT. In the case of the DT, it's easy to make sure none are in eyesight if the endpoint.

2) No, the laser does not touch the exterior of the tank. It's held just away. I make sure there is a slight angle so that any reflected energy is not directed back at me, or the laser.

3) Yes - The beam reflects off of every tank surface. You have to account for all angles. You also have to be cognisant of what's behind your target in an case your hand shakes, or for when the target shrinks. Just a couple second strike will damage any coral.

4) I'm not sure as I haven't been able to find a high power 405nm yet. Using a 1.8W 445nm, I haven't noticed any power drop off when working at further distances - although my tanks are small and my max distance is ~24"

5) +1! I agree wholeheartedly. As shown in the second post of this thread, mine are kept under lock-and-key.

[landy]

I purchased a 560mw 405nm laser from a member of the laser pointer forum. After testing, I have come to the conclusion that it does not have enough power. Using a 1 minute on 1 minute off duty cycle, it takes way too long to cook even small Aiptasia.

So, either I’m going to give up on the 405, or spend the cash for a G1 lens… Haven’t decided which yet. Just thought I would share my findings.

Landy

[CalmSeasQuest]

Originally Posted by landy

I purchased a 560mw 405nm laser from a member of the laser pointer forum. After testing, I have come to the conclusion that it does not have enough power. Using a 1 minute on 1 minute off duty cycle, it takes way too long to cook even small Aiptasia.

So, either I’m going to give up on the 405, or spend the cash for a G1 lens… Haven’t decided which yet. Just thought I would share my findings.

Landy

I don't think a G1 will provide enough increase on a 560mw laser to warrant the purchase (unless you were going to use it on a later host.) If you decide to try it, make sure your host will accept a G1.

405nm is not the problem. For our purpose (underwater burning) I beleive it requires at least a 1W laser, with more being much better. I can see a distinct difference between my 1.2W and 1.8W hosts. You can probably accomplish the task with 1W, but it will require longer lase times, pushing the duty cycles of the laser.

More isn't always better, but as it pertains to lasers for use in aquaria, I believe there are distinct advantages to higher power output.

[jrpark22000]

Originally Posted by CalmSeasQuest

More isn't always better, but as it pertains to lasers for use in aquaria, I believe there are distinct advantages to higher power output.

I agree. My 1.4w does great on small dark pests, but more power would be better. Light colored critters like a ball anemone and xenia take multiple hits to eradicate.

Xenia and large palys are the only 2 items which give me trouble. They always seem to grow back after a week or more. My solution has been to lase them to a grey blob, then reach in and scrub the rock to dislodge. I then filter the floaters off with a sock on my overflow. I usually wait a day in between the lase and scrub but only do so to verify the pest does not started to recover overnight.

Also an update on vermetid snails. Fry them for much longer than you think necessary. Also you must be able to lase the very bottom of their shell. They retract to the smallest part of the base once threatened. The calcium shell is an effective heat shield and requires a longer treatment.

[CalmSeasQuest]

I had a few moments this morning to test the underwater 1.2W. Initially my prior problems reappeared, being unable to obtain a fine enough focus point to achieve burning - then it dawned on me. Air was trapped in the hood containing the lenses. Once I inverted the laser underwater allowing the air to escape, it functioned just fine. I observed the following,

• Although the lower power output is noticeable, I think it is mostly offset by being able to place the laser much closer to the target and by avoiding any power loss due to reflections off the tank walls.
  
• The cooling power of the water if significant. This laser has a 60 second duty cycle. When used outside the tank, the laser would be very warm to the touch after a minute of lasing. When used submerged, the duty cycle seemingly becomes irrelevant (at least as far as thermal management - there may be some advantage in allowing the batteries to recover) as I detected no temperature increase despite many minutes of continual lasing.
  
• When used underwater, it seems the battery capacity will become the new duty cycle. As this host uses smaller 16340 cells, I noticed a significant power drop off after ~5 minutes of use.

So far, it looks like the underwater option is viable and likely a safer option as potential reflections are minimized. Because you're able to work much closer to the target, you're able to use your hand to at least partially sheild the beam endpoint from the tank's inhabitants.

[Landsailor]

Water is a vastly superior conductor of heat compared to air. You can easily spend all day in a 75°F room, but try the same thing in a wetsuit in water and you'll be ready to get out much sooner. Water has a thermal conductivity of .67W per meter/Kelvin and air is like .03 or something. (very dusty mental file)

Any time a wave transitions from one media density to another, it will be affected. In this case, air to saltwater. That's why it didn't work well until you voided the air.

It may not need to be typed, but be sure you rinse it thoroughly in freshwater after using it.

Here's one useless trivia fact related to salt and lasers: Some of the purest, most expensive laser table lenses in the world are made almost entirely of salt. Needless to say, humidity is not allowed in those enclosures!

[TheFishMan65]

CSQ - I don't know exactly how the laser is manufactured. But the heat probably has to go from the LED, through a board to a heat sink, then from the heat sink to the out side case. Hopefully each interface conducts heat well, but I think the laser could still overheat in water if you have poor heat conduction.

You'll need to make your own decision, and what is right for you may not work for others.

[CalmSeasQuest]

Originally Posted by Landsailor

It may not need to be typed, but be sure you rinse it thoroughly in freshwater after using it.

Thanks Landsailor - Water is truly a great conductor. As for rinsing - Rinsed, dried and returned to their locked case

Originally Posted by TheFishMan65

CSQ - I don't know exactly how the laser is manufactured. But the heat probably has to go from the LED, through a board to a heat sink, then from the heat sink to the out side case. Hopefully each interface conducts heat well, but I think the laser could still overheat in water if you have poor heat conduction.

You'll need to make your own decision, and what is right for you may not work for others.

Great point - I haven't disassembled this one to determine the heat sinking setup. I based my conclusion on the fact that I can sense no heat whatsoever at any point on the host after underwater use, whereas it's warm to the touch just moments after use in air.