Initial PAR results

Hi all,

I just received my Apogee quantum meter with remote sensor and took a few quick measurements for fun, while I work out a measurement grid

I also purchased the leveling platform. It has a little level glass viewer as well as three adjusting pins.

Quick and easy to use and very responsive to small sensor placement changes.

Using 2 30 watt Verilux brand regular flourescents mounted 7.5" above the surface on a 45 gallon 24" tall tank:

1. Just at the surface with the sensor ABOVE the water: 50
2. Just at the surface with the sensor BELOW the water: 40
3. Placed on the substrate: 20

Going to the 3x150 MH 6500k setup also at 24" depth of tank:

I just placed the sensor in two places while I adjusted the lights. Top and bottom directly in line with each other.

17"

1. Sensor above surface: 215
2. Sensor below surface: 175
3. Sensor on substrate: 55

14"

1. Sensor above surface: 250
2. Sensor below surface: 215
3. Sensor on substrate: 65

11.5"

1. Sensor above surface: 345
2. Sensor below surface: 300
3. Sensor on substrate: 75

It is amazing how the PAR rate changes even moving the sensor a little bit. I know MH have a bad spread, but it is really ridiculous when you see it.

Plus, the amount of reduction between under and over the water line is dramatic.

In some of the plants beds at the substrate, I was reading only 10-15 even though the growth looked good, no algae, and some pearling down there.

Of course, these are just first quick impressions, that I wanted to share.....

Just very interesting stuff. Nice to have a few facts for once.

P.S. all the above is null and void due to possible operator error lol

P.P.S. If anyone is in the WPB, FL area and wants to use it, PM me and see if we can meet to say hi and take a few measurements. It is quick and easy.

 

Vaughn,

Hope you didn't waste too much time....

I looked here at the specs and there is no mention of if it is a ' hemi-spherical sensor ' or not. The sensor looks like a small molehill shape if that makes any sense with the sensor on top. The level view glass is built into the platform.

It is as stated, very sensitive to ANY movement. The platform though at least kept it steady in my two measurements, as the gravel supported it nicely in one case, and I rested it on one of the cross frames for the other. Both times, the level viewer showed 'on target'. Even when I placed it just under the surface, I was able to hold it steady enough to get a constant reading.

The platform is heavy steel(?) and very useful and I also was able to balance it on wood or stones at various levels in the tank to get readings. No wonder plants grow better the closer they get to the surface lol

As an example, placing the sensor on one of the two cross bars at each end and center gave the following numbers going center-back-front:

Bar 1: 336-91-106 at 17.5"
Bar 1: 396-116-71 at 14.5" I think this last number is LESS because the spread is less with the light closer to the water.

My lights are somewhat off center as I had to use the studs for the weight and the tank would have entered the hallway if I had centered it, oh well. So the bar may get a bit of two lights as opposed to mostly 1, if that makes sense.

I can slide the lights back and forward as well, as a slight slant from left to right and back to front as they simply rest of closet hardware......so they are very mobile at each height adjustment.

Quantum Meters: Apogee Instruments: SPECTRAL RESPONSE

Not sure how much operator error there can be, as the unit consists of the sensor and an on/off switch, which I was able to figure out

I just wanted to put this out, because if these numbers made no sense, I would know right off..I was able to keep my hand steady (???) to get a decent reading.

What did you find 'interesting' about them, BTW??????

Just for fun, moving the sensor slowly, changed the measurements rapidly with it, but I am unsure if this is a proper use of the device., in that it needs to be stable and unmoving for a correct measurement to occur. I would expect that to be the case.

More seriously, I was thinking of the following basic pattern:

I have 3 lights with lenses rectangular in shape.

I would take 5 horizontal measurements for each light at each corner and the middle of the lens. 5 x 3 = 15 readings.
I would then take 3 vertical measurements, at just under the surface, mid-water (12"), and substrate (23"), as close to the 5 horizontal points as possible. 3 x 15 = 45 readings.
I would then take 6 vertical measurements, 3 at each end, corner, middle, and corner. 6 x 3 = 18 readings.

Plus a few tossed in under plants, in thickets, under wood, etc, and I think I would have a decent matrix to map the low to high light areas.

Thoughts?

I am probably like a mad scientist misusing a perfectly benign device to take over the world.....

 

Tom,

Yes, the practical is more of what I am after.

My whole intention is too look at the things you suggest, and make better scaping/planting choice decision, based on that type of data.

I was just intitally surprised at the amount the light decreased with just small increases in distance..........

I was guessing and experimenting before... If a plant did not do well, in a location, I would try moving it to another and see how it did there.

While I am doing so, I will record as much as possible. That should give Vaughn some better data, if he would be kind enough to plot it again.......

Vaugh,

I would say the bulbs are recessed about 1-1.25" in the fixture if you measure from the inside of the lens. No way 4". I will measure accurately later..........

I just adjusted the lights so the bottom of each lens is exactly 9" above the water surface.

Will take some new measurements at that height.

I intent to use this height for all the other readings that I will do.

I think I will use several pieces of PVC anchored in the substrate at various lengths, to place the sensor on. Then I can have it steady, and be more assured that my 5 point pattern is at least at the same height for each bulb.

I think then that the same set of readings at 1 and 2 week intervals would be interesting. I will do no pruning in that time.

Thanks for all the info and advice.

Will post all results (and of course questions).

 

Hi Vaughn,

I would never accuse you of such a thing!

In the software development world, they call that 'hard-coding' a variable lol

So, I took some quick readings of the substrate, as I want to grow some HC or glosso, and a few of the surface for a quick compare.

Lights are exactly 9" above the surface on a 24" tall tank.

Substrate readings:

Range: 10-110 based on where it was. Highest readings were directly under the bulbs, and the lowers were in the shade of plants and wood and at the very ends and corners of the tank.

Open areas where I want a ground cover range from 55-100. This is just dragging the sensor around with me. Was kinda fun and easy.

Some of the lower readings (55-70) were under the shade of some wood or other plants but still in the middle of the bulb area. So shade can have a dramatic affect.

So, I had readings of 15-20 at the feet of L. inclinata var cuba and this is a pretty thick bunch. All leaves are fine and green at the bottom, and get bigger, browner up top.

Same with L. aromatica with no algae and nice leaf formation.

The tops of the aromatica are about mid-water (12-14") and in a pretty close bunch. Taking readings at the plants tips ranged from 90-370 with the sensor never moving outside of a 4" circle. These are placed pretty much between two of the bulbs. However, one of my braces is in the middle of the bulbs.

Lower readings had smaller, greener, leaves. The highest readings were slightly taller, more colorful, and bigger leaves, but all were pruned level at the same time recently.

Surface:

I held the sensor directly under the water beneath one of the lights. Moving the sensor around slowly and letting the display 'settle', produced a range of 350-650 with the highest directly in the middle of the lens

Again, bringing the sensor just ABOVE the water, made a huge difference of at least 75-125 from just UNDER the water. This was consistent with placement.

So, very interesting stuff, and I am very glad I have this meter.

I totally recommend any club investing in one if they can.

So, surface to substrate under the one light produced a high of 650 at the surface and a high of 110 at the substrate directly in line. Well, close anyway lol

Will post more as I have it.

 

Jeremy,

NP. Happy to share it.

Ok, I'll jump in with my thoughts............

How about the theory that the importance of inner vs outer leaves, changes through the life of the plant. However, generally, I would say the larger leaves.

As an example with your swords, the new growth always starts at the center, or the growing tip. The outer leaves, as they are larger, are MORE responsible for nutrient retrieval than the tip, as these leaves need to produce for the entire plant.

I assume the tip can also assimilate, more as it grows, but am thinking that the growth rate of the tip is greater at first, and consumes more than assimilates. I think this equals out and goes the other way as the leaf grows.

As the outer leaves start to get older and larger, they fall outward, and they tend to die off and disintegrate. I think this is the plant eliminating older leaves that are now also consuming more, but contributing less. This also opens the growing tip to MORE light and nutrients, so it can take it's place in the cycle.

I know that the old rule to control large swords is to be ruthless with the new leaves, and not to let them get too large.

I think that by constantly trimming the larger leaves, you impact the overall ability of the plant to assimilate light and nutrients, and the TOTAL amount of nutes available to the plant is less, and it thus stays smaller.

The larger leaves have more surface area to catch light and intake nutes, so overall, I would say that the larger leaves are generally more reponsible for intake of all nutrients.

I also am finding that REGULAR pruning really makes a big difference. Stems tend to get thick very quickly, more so than we think. These areas tend to get very dark and lose a lot of flow. Less algae and better overall growth when a little thinner.

Thoughts? Or am I way out there on this?