How does height above the water affect PAR, or more importantly, coral health?

[oreo54]

Heard first hand experiences of seneye being as much as 100 par off. Read alot of bad reviews as well. I almost bought the neptune sensor to use with my apex.. but the sensor is the cheaper sensor. And has bad reviews.

Cheap test equipment would put me in no better position. I'd still be running the system and making adjustments.

You will probably need to make adjustments regardless of par meter or not, to be honest.
As to errors well as long as they are consistent it is just used as a comparison.
I like to think about my Seneye in this manner. 2 readings both at say par 100. If 100 or not I at least can assume similar output between the 2.
Unless I'm comparing say a 6500k environment with an "actinic" one.

I couldn't agree with you more that a QUALITY tool is what one wants.

At the time I bought mine they and an Apogee "new model" were both on sale.
I bought the Seneye because, at the time, Seneye didn't have any issues per numerous tests between the brands.
It seems only later models had issues
It isn't a great sensor response compared to Li-cor or new Apogees and lack of cosine correction makes it a bit tricky to use though.

Not trying to talk you into one since I (for a while until even newer models were released by Apogee) regretted not getting the Apogee.
I still find it more useful than eyeballs, lux meters, or phone apps..

 

[Drewbacca]

i read through the whole thread but didnt see anyone tell you ...you can just RENT an appogee par meter. Some LFS like mine rent them.. but So does.. BRS.. They have you 'buy' one for legal reasons since they can't "rent" But, you have TWO MONTHS to return it..(i think) and they will refund all your money MINUS a 'restocking fee' *cough,rental charge,*cough.
They want you to use the right equip, & be successful by Knowing the true PAR values. Like many mentioned here.. its the only way to truly ensure avoiding negative impact on your corals with a light swap or initial setup. Also brs has already made videos on almost all name brand lights like the neptune sky and what all the par values are at multiple mounting heights & water depths. While you have the par meter, set up your old lights or at least one over an old tank (if you have one that holds enough water and get an idea of what it was before too. Or actually just hold over current tank for a minute and read. Give us an update when you can. Im sure all those who replied many times to help you would like to know.

 

[Hooz]

i read through the whole thread but didnt see anyone tell you ...you can just RENT an appogee par meter. Some LFS like mine rent them.. but So does.. BRS.. They have you 'buy' one for legal reasons since they can't "rent" But, you have TWO MONTHS to return it..(i think) and they will refund all your money MINUS a 'restocking fee' *cough,rental charge,*cough.
They want you to use the right equip, & be successful by Knowing the true PAR values. Like many mentioned here.. its the only way to truly ensure avoiding negative impact on your corals with a light swap or initial setup. Also brs has already made videos on almost all name brand lights like the neptune sky and what all the par values are at multiple mounting heights & water depths. While you have the par meter, set up your old lights or at least one over an old tank (if you have one that holds enough water and get an idea of what it was before too. Or actually just hold over current tank for a minute and read. Give us an update when you can. Im sure all those who replied many times to help you would like to know.

I came here to say this. Rent one! If you have a semi local reef group, see if you can borrow one. A local LFS here rents one for $25/day, BRS does their "rental" so check around your area. They are absolutely essential to getting things setup as well as you can and giving your coral the best shot.

As for "how to know" if the coral will respond, there are general PAR guidelines depending on what you're trying to keep. LPS and softies generally like 75-150 PAR, SPS will generally do well in 200-350 PAR. If you get your hands on a meter and setup your light in those ranges, then chances are VERY good the coral will grow and color well for you (as long as other parameters are maintained).

BRS videos also do a pretty good job of covering mounting height spread and spectrum settings, so I'd also strongly suggest watching their review of your light.