So I tested par and have a question..

[Mattj815]

So I rented a par meter from my lfs. An apogee sq 420. Its the usb plug in model.

While it wasnt perfect or that easy to use (didnt have the wand) I feel it at least gave me some ballpark numbers to go off.

My main question is, on the right hand side of the tank my par got higher the lower I went. Like it was higher in the sandbed than the water line. At first I thought something was off. Then thought maybe due to the spread??

Does that sound logical?

I have it for one more day and am hoping to play with a little more tonight. I just thought numbers would be a bit more linear in regards to depth.

Tank is a nuvo40 and light is reefbreedera photon v2 16inch. About 10 inches above the tank

I didnt get to test all the spots I wanted to with rock being in the way and also having to hold the sensor. Which also prompts another question. With my hand and arm in the way im wondering how much it could have skewed the readings?

I was gonna try a makeshift wand but doubt ill have time (working late tonight)

Another lfs has a meter out on loan. I might rent that just to compare.

Thanks

 

[Hydrored]

So I rented a par meter from my lfs. An apogee sq 420. Its the usb plug in model.

While it wasnt perfect or that easy to use (didnt have the wand) I feel it at least gave me some ballpark numbers to go off.

My main question is, on the right hand side if the tank my par got higher to lower I went. Like it was higher in the sandbed than the water line. At first I thought something was off. Then thought maybe due to the spread??

Does that sound logical?

I have it for one more day and am hoping to play with a little more tonight. I just thought numbers would be a bit more linear in regards to depth.

Tank is a nuvo40 and light is reefbreedera photon v2 16inch. About 10 inches above the tank

I didnt get to test all the spots I wanted to with rock being in the way and also having to hold the sensor. Which also prompts another question. With my hand and arm in the way im wondering how much it could have skewed the readings?

I was gonna try a makeshift wand but doubt ill have time (working late tonight)

Another lfs has a meter out on loan. I might rent that just to compare.

Thanks

It doesn’t sound right. I have a 510 with a wand, any shadowing that you are creating with your arm will impact it

 

[Potatohead]

Sometimes on the very edge of the tank the par will be lower at the bottom than in the middle because there is light bouncing off the glass and reflecting back. If you use the meter on clean glass and then three to four day algae growth glass you will see a par difference in these areas. Also if you go outside the spread at the top corner of the tank obviously the par will be lower than further down.

 

[Silent]

Just use a zip tie and an algae wand or something similar to use instead of holding the sensor. You could even use duct tape or Velcro if you had to in a pinch.

 

[Mattj815]

I was definitely trying my best to hold the sensor oit from my hand a little bit to reduce blockage.

Didnt think about bouncing off the glass.

Like I said im happy I got it to at least give me a number to work off. I was suprised at the number full.power mid tank. So Im kind of happy I jusy recently reduced settings to see if things would be happier. And they seem to be. Might bump a little over the next few weeks and stay there for a while.

 

[BeejReef]

Yeah, so having your arm as a variable probably isn't ideal.
That aside, getting higher levels at the sand is odd. I'd guess you've got it figured correctly as related to spread.

10" isn't low, by any means, but it's not that high either, considering it's a two foot tank and a 16" light. If you're measuring off to the side of the light at all, you could see how the par might increase as you get low enough for more and more of the diodes to be hitting the area you're measuring.

If you're seeing this odd phenomenon directly under the center of the light, then I'd guess there's something wrong with the par meter. Assuming it's not that, you might raise your light up a bit. It's probably ok to miss the corners and extreme sides at the top of the tank with your mounting (who mounts corals there... lol), but you'll want your light high enough that your prime, mid-tank, mid height real estate is getting a proper distribution.

 

[Mattj815]

Yeah, so having your arm as a variable probably isn't ideal.
That aside, getting higher levels at the sand is odd. I'd guess you've got it figured correctly as related to spread.

10" isn't low, by any means, but it's not that high either, considering it's a two foot tank and a 16" light. If you're measuring off to the side of the light at all, you could see how the par might increase as you get low enough for more and more of the diodes to be hitting the area you're measuring.

If you're seeing this odd phenomenon directly under the center of the light, then I'd guess there's something wrong with the par meter. Assuming it's not that, you might raise your light up a bit. It's probably ok to miss the corners and extreme sides at the top of the tank with your mounting (who mounts corals there... lol), but you'll want your light high enough that your prime, mid-tank, mid height real estate is getting a proper distribution.

So I just ordered reefbreeders light mount which mounts the light at 10" i wanted to get rid of the leg mounts bc I cant keep the lid on flush and already lost a diamond goby. So I think im stuck at that height.

But the middle of the tank seemed to have more par the higher I went. It was hard too bc the levels would bounce around so much as I was measuring. Is this normal? I chalked that up to keeping my wave.akers and pumps on thinking its the normal tank conditions.

Im now eager to rent the other meter and compare.

 

[BeejReef]

Ahh.. the pumps were on too!

Honestly, I guess that makes sense, since the pumps are going to be on 99% of the time, but you probably do get more turbulence near the sides/powerheads.

Still sounds like you might not have enough light spread. Sorry about your Goby.
FWIW, I run budget lights as well and have really enjoyed running a canopy. It hides your <$2,000 lights, allows you to mount them high and run them bright to get very nice coverage without a ton of light spill in the room, and you can put your netting or egg crate above the lights in the canopy. It keeps your fish in and doesn't restrict your access to the tank nearly as much as a flush-fit cover.

 

[Bpb]

At the edges of a tank the light will be more intense the lower you get. You’re collecting more photons hitting the sensor from diodes farther away that will illuminate the sandbed but not the surface. Also from glass reflection. What you’re seeing is perfectly normal.