Use of Lasers in Controlling Pest Algae and Corals

[CalmSeasQuest]

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]

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]

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]

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]

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]

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]

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]

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]

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

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.

 

[TheFishMan65]

For those that may not understand I will try and explain heat transfer in laymans term (so you can understand my concerns). Please not I am not an expert so if I get something wrong please correct me.
In an ideal case the LED will run at some temperature say 100 degrees. It will conduct perfectly to the heat sink the the heat sink where the LED touches will be 100 degrees. The other end of the heat sink will source the heat somewhere lets say 0 degrees. in the ideal case that side would be 0 degrees. The center of the heat sink roughly 50 degrees.

Water is a much better conductor of electricity so it keeps that side of the heat sink pretty much at water temperature. If the heatsink can't transfer the heat fast enough though the LED could reach 200 degree, the middle 100, but the water side is still water temperature.

There are two issue how fast can the heat be moved from the LED and how fast can it be dissipated. Water dissipates faster, but if the heat can't get away from the LEDs it won't matter (to some degree).

Hope this helps.

 

[CalmSeasQuest]

Thanks Thefishman65. I certainly understand and agree with the concern. That said, I'm comfortable with extending the duty cycle when used submerged. At next use, I'll take some temp reading with my IR thermometer at various points. I *think* it will be OK as I can't detect any temp increase - even in the front of the laser where the diode resides opposite the heat sink. It's certainly possible I could kill it, but at least it will have died in the name of science

I've been getting a lot of questions regarding the effectiveness on specific pests. Here's what I've noted so far. Listed in order of ease of eradication (easiest to most difficult)...

• Hydroids
• Aiptasia (very easy to eradicate as long as you have line-of-sight to the attachment point.)
• Valonia
• Clove Polyps
• GSP
• Vermetid snails (The small ones are simple - The large ones require very long lase times - and you have to focus at the base, well behind the snail when extended.)
• Majano
• Red Turf Algae
• Xenia

My "focus" has been on Xenia as all else has been relatively simple to eradicate. Xenia is proving to be the greatest challenge. I agree with jrpark22000s comments - It typically takes multiple sessions over the course of a few days to completely kill it. You basically have to lase it until it's little more than a "blob" to prevent it from regrowing.

The very fine, "wispy" algaes such as hair and bryopsis are also resistant, seemingly due to how effective water is at cooling. Even they can be destroyed by focusing on the attachment points, (especially in small patches) but it takes much longer and would not be practical for large amounts.

I have also found it useful in "pruning" SPS to eliminate encroachment and the resulting chemical warfare (especially Montis.) I theorise it might also be a useful in cases of RTN - in essence, cauterizing a border, thereby separating the healthy tissue from the area of RTN. Thankfully I haven't had it occur to test.

I've also been asked about Zs or Ps. While I haven't targeted any, I see no reason why it would not be effective. The general rules seems to be that lighter colored - larger mass items will take longer to eradicate. Any coral or pest I can imagine could be destroyed by a laser. It's simply a matter of how much lase time would be required.

 

[CalmSeasQuest]

One other observation - After extended lasing session (Xenia) I noted that there is about a 20 point drop in ORP (440-420) which gradually recovers over the next few hours. I'm uncertain what is causing this, but it seems reasonable that organics might be released into the water column.

I've only noticed this thus far when lasing Xenia and I have not noted any negative impact form any other corals in the tank (including those within an inch of the targeted pests.) I run ROX 0.8 carbon on a continual basis.

 

[CalmSeasQuest]

Both lasers (waterproof and non) continue to work very well. I find that I am working more from outside of the tank, alternating duty cycles with both lasers.

Every pest targeted except for Xenia has been easily eradicated with the laser. Xenia continues to be a challenge. I've been able to contain it, but haven't had the patience to completely remove the larger patches.

I'm convinced the laser can be a very valuable tool as long as safety protocols are observed.

 

[wilsonreefs]

Both lasers (waterproof and non) continue to work very well. I find that I am working more from outside of the tank, alternating duty cycles with both lasers.

Every pest targeted except for Xenia has been easily eradicated with the laser. Xenia continues to be a challenge. I've been able to contain it, but haven't had the patience to completely remove the larger patches.

I'm convinced the laser can be a very valuable tool as long as safety protocols are observed.

OK Tom,

You either need to come to my house and get rid of my mojano, actually not very much at that (at most maybe 10 stalks), loan me your lasers, or last but not least.....tell me where to buy them. Very good information, Thanks for the extensive research and sharing with everyone. Well done!

Carl