PO4 probe and par meter

[LISound]

anyone have either. trying to dial my tank in.
if not, maybe we can pony up some cash and get one for our group.

I know folks didn't want dues or the like but it might be worthy investment considering our group is fairly small.

I know Ctars has a par meter but I'm not sure everyone here is a member. And I can't make any of the meetings.

scott

[scolley]

I'm all for a PAR meter. But I don't know how you get one in a club with no dues. I can think of one way - I'm willing to make this offer...

I'll buy a par meter (roughly $100). I'll rent it out to any interested club member for 30 days. But the stipulations are:

you pick it up at one club meeting, return it the next. not 2-3-4 meetings later. the next meeting.
that rental is $10.
deposit is $100 cash (with rental that's $110).
lack of return of functional meter at the next meeting is forfeiture of deposit, which I will use to buy the club a new meter.
after the 10th rental the rental money goes to our yet-to-be-elected club treasure for deposit in club funds.

The way I see it, I'm hard pressed to make any money off this. Members get access to a par meter at a fair rate. We never go more than 30 days without one (time between someone not returning it in time and my having received a new one in the mail). And it encourages meeting attendance.

Thoughts?

[LISound]

sure, as long as I get it first. :)

[scolley]

Hey, if I do it, it's only right that you are first!

But I'm surprised that no one else bit on that opportunity. I'm not particularly interested in holding the bag for most of the cost of an underwater light meter.

Anyone else have an interest "renting" a club light meter for a month for $10?

If even a few people chime in I'll be happy to do it.

[wboyden]

I will put in my 2 cents (or 10 bucks in this case)for whats its worth, Not sure if I would considered a member or not.. and I have the hardest time trying to make meeting but I guess if I rented the thing it would give me more of an excuse err... reason for going..lol

[rjinct]

Hey Steve -- sounds like a good idea as long as you are OK fronting the money instead of earning $1.40/year from a CD at Peoples!

[scolley]

I'm cool with fronting the money for the club. Problem is I'm serious about the $110 cash, with the $100 deposit returned the next meeting in return for the working meter.

If I do it I'm just not playing the "will you take a check?", "I forgot, can I bring it next month?" games. Then it becomes a PITA for me. Not into that.

This way it's "Forgot to bring it back? That's ok, 'cuz now you own it."

Simple. ;)

[LISound]

I guess if you have to part with $100 for a month...cash, that might be tough on some people. I know once it's out of my pocket--out of mind. that would be like found money the next month.

Maybe it's easier to just grab the one from the club. I only want to test what my old bulbs are putting out compared to new ones after 12 months. t5's. Only need the meter for an hour---

we'll see if anyone else chimes in.

[scolley]

Agreed. That's why I made is so painfully clear about how it would work - 'cuz I figured they might not be reading the details so clearly.

Now for the club to have one, all you need is about 10 people to part with about $10 to "share" it on a trusting basis.

Me personally, I think having one is a great idea (!), and will support it in whatever incarnation people are willing to stand behind. :)

[tank o tang]

I'm in. I can chip in the $10 or rent it when needed. I like the chip in method and only lent out to Active members. Only thing that sucks is what happens if it craps out by no fault of the user. I'd hate to take somebodys $100 and give them the it sucks to be you in the end. If the active members are interested in making an equipment bank for people to borrow from on a monthly basis in emergencies I have some I can donate to the cause.

[scolley]

Sounds like we might have 5 people to chip in $10. If we can get about 5 more we should be able to get a club par meter. Not a "rent" for $10, but a paid for by the generosity of 10 members, so use would be free.

Can we get 5 more people willing to chip in $10?

[tank o tang]

I wouldn't mind having people pay a minimal ($2) rental fee and a 50% deposit to aid the purchase of future club equipment. Deposit can always be returned as long as it is brought back working or not as long as there are no signs of abuse.

[LISound]

sure, I'll even throw in $15 :)

[RTMA]

I'll chip in 10. Don't really need the service atm, but having the option in the future is worth it.

[wboyden]

I wouldn't mind having people pay a minimal ($2) rental fee and a 50% deposit to aid the purchase of future club equipment. Deposit can always be returned as long as it is brought back working or not as long as there are no signs of abuse.

Sounds like a good to me, I am going to try and make the november meeting 90 minute drive though

[scolley]

Well this whole discussion may be moot. I was referring to our purchasing a PAR meter, but was thinking about the pricing of Lux meters. After a tiny bit of research it became clear that PAR meters cost 4-10 times what a Lux meter costs.

Not technically we could get a Milwaukee Instruments SM700 Lux Light Meter,but to get the total reading for the ranges we are talking about in a reef tank, it could require taking three separate reading for each spot we are measuring. Adding them up would come close to a true PAR reading. Kind of a PITA. But a whole lot less expensive.

Figured I'd bring it up for our consideration. :(

[LISound]

we'll see if we can collect some cash at the next meeting.

[Obi-dad]

The drawback to using a lux meter is that it doesn't read blue light as well as other wavelengths, and since I use 20k bulbs there is a lot of blue light (even the PAR meters don't have perfect linear response to different wavelengths, but they are better than lux meters). I have borrowed the CTARS Apogee Lux meter a few times, and compared it's readings to my cheapo Lux meter. I now have a conversion factor that works for my lighting setup (I just multiply the lux reading by this number to get PAR). So now I can use my lux meter to gauge when to replace bulbs.

What I am getting at is that if you really just need a PAR meter to check when your light levels have decreased enough to warrant changing the bulbs, you can use a lux meter to do that. The PAR meter is cool because you can compare to readings like on Sanjay's bulb tests, etc, but IMO isn't absolutely necessary. And Lux meters can be had for about $30.

[scolley]

Greg,

The SM700 senses a peak of 560 nm. Wouldn't that capture your blues?

Also, what I said about three readings in my prior post was incorrect. Only one would be needed, it just has to be set for one of three light intensity ranges:

0-1999 Lux
2000-19999 Lux
20000-50000 Lux

[Obi-dad]

No, 'blue' is around 450nm, and violet is around 420nm. 560nm is yellow I think (700nm is the end of the red wavelengths). The visible light wavelengths and our perception of colors is not linear, violet is a narrow range of wavelengths, while red is much wider.

[nakama]

I'm in! Whatever way you decide to go.
Neil

[wboyden]

I was doing some reading on light fixtures as I am getting ready to get some new lights. and i was told that a LUX measures lumens and a PAR meter measures photosynthetic light.

How does this differ?

[scolley]

In a nutshell, a layman's explanation would be that a PAR meter's readings include the total light intensity for the the full set of frequencies (colors) of light that used in photosynthesis - precisely the frequencies that we are interested in measuring. A Lux meter, on the other, typically provides the total light intensity for a small range of frequencies. Typically they measure the normal "daylight" frequencies pretty well, as they are - by design - skewed to measure light perceived by the human eye. But as Greg indicated above, his Lux meter does not measure blue frequencies. And many of us - myself included - are very interested in getting a reading on that light also.

[Obi-dad]

To be precise, PAR meters measure more of the frequencies we want to measure than the Lux meters, but they also have a 'response curve' that under-represents blue and some of the red. If you go to the Apogee website (one of the popular PAR meters used in the hobby), you can see a graph of the response curve. Apogee response curve (http://www.apogee-inst.com/quantummeter_techinfo.htm) In that graph the blue and violet are in the 400-450nm wavelength range, and the red is at the 700 end.

The net result is you get a better reading from the PAR meter than the Lux meter, but whether you need a PAR meter or lux meter depends on what you want it for. If you just want to tell when to replace your bulbs due to declining output, you can use a Lux meter (much less expensive).

[Wheel of Time]

Scolley, I have not done any real research into a lux meter, but you and Obi-dad seem to know quite a bit. How much are a few of the ones worth purchasing. Forget about the real high-end as Im sure that is way more than we/I want to spend. Do you have a sense of 2-3 different reliable brands/models and price ranges to compare?

po4 probe would be handy too. Im still low tech using mostly test kits (do have the ph and temp probes though, but still no controller). I am tiring of test kits... I need to just bite the bullet and get a controller!

[scolley]

Well, I'm not the most informed. But as I understand it, cheap lux meters are dirt cheap, as has been stated here. But you can't get them wet. They are suitable for telling you when to change your lights. Personally I've got no interest in those.

I'm personally interested in at least a submersible lux meter - where you can measure how much light is in a particular spot in in your tank is getting. Those appoach $100, but they have the 'not measuring all the light' problem. The same submersible capacity in a par meter is a bit north os $300.

Or at least that's how I understand it.

[terahz]

I have a foot candle meter if anyone wants to use it just let me know. It looks like this:
http://www.hydrofarm.com/image.php?image=/i/jpg/LG17000_31652.jpg
manual: http://www.hydrofarm.com/downloads/fc/17911_LG17000.pdf

It is not for underwater measurements, but I'm sure if you put it in a Ziploc bag it will be fine.