Bad PAR readings AI Prime

[Rick's Reefing Adventures]

Hello,

I have a 25G Waterbox peninsula that is mostly acropora-dominated. I’m currently running two AI Prime 16HDs above the tank with the attached schedule.

I have a couple of questions:

First, I’ve noticed that my PAR readings are actually lower when flow is turned off. That seems counterintuitive to me. I do have a lot of surface agitation—could that be affecting the readings?

Second, I’m measuring around 200–230 PAR. The lights are mounted about 20 cm (≈8 inches) above the water, and my acros sit roughly 10–25 cm (≈4–10 inches) below the surface. This feels low for an SPS-dominant tank.

Would adding a third Prime make a meaningful difference? Right now I have two lights spaced evenly, but I could reposition them and add a third in the center. My goal is to reach at least ~350 PAR.

My acros have decent coloration, but growth has been very slow for most of them. I didn’t realize this might be a lighting issue until I started measuring PAR.

If a third Prime won’t significantly improve things, I’m considering selling them and switching to something like a Radion instead.

Thanks!

 

[rtparty]

Which PAR meter?

With flow on you will get numbers bouncing around while taking measurements. Surface agitation can act like a magnifying glass as the light interacts with it.

I test lights with flow off so I can get a good baseline and not deal with the numbers bouncing all over the place.

 

[areefer01]

You have 2 x 60W lights over a 25 gallon tank. What is the PAR number with every channel at 100%? Test with 1 light on, then 2, so you get an idea. I don't remember the lights exact break down but you will have 4 white, 4 blue, 4 royal blue, then a couple of others. You start dialing down channels to get your spectrum of choice and PAR numbers may decrease. Something to be aware of. That can also be tested.

For what it is worth there is more to success than a number.

 

[Rick's Reefing Adventures]

Which PAR meter?

With flow on you will get numbers bouncing around while taking measurements. Surface agitation can act like a magnifying glass as the light interacts with it.

I test lights with flow off so I can get a good baseline and not deal with the numbers bouncing all over the place.

I expected PAR to be higher with flow off for some reason. I use a Apogee meter. If I test PAR with flow on, won’t that be more accurate to what the corals are actually receiving with flow on?

You have 2 x 60W lights over a 25 gallon tank. What is the PAR number with every channel at 100%? Test with 1 light on, then 2, so you get an idea. I don't remember the lights exact break down but you will have 4 white, 4 blue, 4 royal blue, then a couple of others. You start dialing down channels to get your spectrum of choice and PAR numbers may decrease. Something to be aware of. That can also be tested.

For what it is worth there is more to success than a number.

I mean the tank is doing great. All corals including acro’s are growing. Lot’s op polyps and everything is going steady. Just slow growth on most acro’s. Also I’ve noticed that when something goes wrong (like a acro that fell over and got a dead spot), it takes longer then normal to grow over it.

Also a big part of primes are unusable. Uv and violet over 70% burns the lens or the leds, moonlight doesn’t add anything, too much white washes out colors and red/green have no reason to be more then 10-15%, maybe 20 if you got a really good UV or like algae.

 

[areefer01]

I mean the tank is doing great. All corals including acro’s are growing. Lot’s op polyps and everything is going steady. Just slow growth on most acro’s. Also I’ve noticed that when something goes wrong (like a acro that fell over and got a dead spot), it takes longer then normal to grow over it.

You mention slow, what are you comparing it to or what is the benchmark? How do you know if it is not related to water chemistry, species, or something else? Looking at the image you posted it seems relatively new.

Also a big part of primes are unusable. Uv and violet over 70% burns the lens or the leds, moonlight doesn’t add anything, too much white washes out colors and red/green have no reason to be more then 10-15%, maybe 20 if you got a really good UV or like algae.

I'm not sure I would agree with this but spectrum is a personal preference.

Honestly if the tank looks good to you, and healthy, nothing wrong with observing while looking down the road at other lighting options if you so choose. Lots to choose from.

 

[Rick's Reefing Adventures]

You mention slow, what are you comparing it to or what is the benchmark? How do you know if it is not related to water chemistry, species, or something else? Looking at the image you posted it seems relatively new.



I'm not sure I would agree with this but spectrum is a personal preference.

Honestly if the tank looks good to you, and healthy, nothing wrong with observing while looking down the road at other lighting options if you so choose. Lots to choose from.

Picture is an older one, also on that picture the tank was running for 2 years haha. I have a good CUC and sold almost all my LPS to try some SPS.

Ofcourse personal preference is a big part. With LPS I ran practically only blue, with SPS I like it white with a blue(ish) tint.

Even though most things in the tank are great, 200-250 PAR is too low for SPS, especially long term. The hardest choice is another prime I can get for 100, or sell my primes for 200 and spend another +-400 for a Radion.

I’m comparing growth to a few things. People in my area with an comparible setup, average growth from this forum and to my easier SPS (monti’s, stylo’s etc).

 

[Science/G]

I don't think you are going to achieve your desired numbers unless you bring up all the channels to close to 100 %

 

[Science/G]

Picture is an older one, also on that picture the tank was running for 2 years haha. I have a good CUC and sold almost all my LPS to try some SPS.

Ofcourse personal preference is a big part. With LPS I ran practically only blue, with SPS I like it white with a blue(ish) tint.

Even though most things in the tank are great, 200-250 PAR is too low for SPS, especially long term. The hardest choice is another prime I can get for 100, or sell my primes for 200 and spend another +-400 for a Radion.

I’m comparing growth to a few things. People in my area with an comparible setup, average growth from this forum and to my easier SPS (monti’s, stylo’s etc).

Get a ReefBreeder Meridian 24 and be done! Actually, I think you can get away with a Meridian 11.

 

[Rick's Reefing Adventures]

I don't think you are going to achieve your desired numbers unless you bring up all the channels to close to 100 %

Definitely true. What would you recommend? A third prime or sell them for a radion?

Get a ReefBreeder Meridian 24 and be done!

Havn’t heard of them. I will definitely check them out. But I do prefer everything in Mobius tbh.

 

[Science/G]

Definitely true. What would you recommend? A third prime or sell them for a radion?

Havn’t heard of them. I will definitely check them out. But I do prefer everything in Mobius tbh.

I had Primes for a while. I burned out the UV lenses twice, and had a fan go. My SPS were meh until I upgraded to the Meridian 24 over my 30 gallon. My LFS runs Radions, they are quality lights, but the Meridians will give you more par for the money and a better spectrum IMHO. They are awesome!
The Reefbreeders app is great. Check out the thread on here.

Reef Breeders Meridians

Anyone else get ahold of the new Reef Breeder Meridians ? My first impression is that these lights are extremely well built! Reef Breeders definitely went above and beyond to top the design of the previous photons. I first started with some 24” fixtures and recently added an edge bar and a 63”...

www.reef2reef.com

 

[Science/G]

Meridian 11

Specifications: Recommended Mounting Height: 10-14" (25-35cm) above waterline with OHM Balance Optics 75watts max power draw Case dimensions LxWxH: 11" (28cm) x 8.5" (22cm) x 1.15" (2.29cm) Weight: 2.85lbs (1.3kg) 12.9" (33cm) long including plug and antenna cover 1.4" (3.56cm) case height...

reefbreeders.com

 

[areefer01]

Picture is an older one, also on that picture the tank was running for 2 years haha. I have a good CUC and sold almost all my LPS to try some SPS.

Np - I was just going off of what you posted.

Even though most things in the tank are great, 200-250 PAR is too low for SPS, especially long term. The hardest choice is another prime I can get for 100, or sell my primes for 200 and spend another +-400 for a Radion.

I think your PAR numbers are off but we'll just disagree. If you are looking for numbers then check out a Nicrew HyperReef 200W. You can pick it up off of Amazon and return it within 30 days if it doesn't meet your needs. You can do a search on the web and get a pretty unbiased review that compares it to the G6 Radion.

Not recommending any light over the other but just providing one for reference/example. There are plenty of lights you can explore for the size tank you are keeping today. Of course another option is to find one that will grow / carry forward should you increase the tank size.

 

[rtparty]

Get a Nicrew 150 for almost 1/3 the cost of a Radion

 

[skey44]

Meridian user and can attest to their awesomeness. My par on the sandbed of 16.5” tank with light 14” off surface most channels around 65pct. App is super easy. I got the shallow reef and I love the spectrum. Awesome blues and still can make a nice daylight look too.

 

[Hooz]

Picture is an older one, also on that picture the tank was running for 2 years haha. I have a good CUC and sold almost all my LPS to try some SPS.

Ofcourse personal preference is a big part. With LPS I ran practically only blue, with SPS I like it white with a blue(ish) tint.

Even though most things in the tank are great, 200-250 PAR is too low for SPS, especially long term. The hardest choice is another prime I can get for 100, or sell my primes for 200 and spend another +-400 for a Radion.

I’m comparing growth to a few things. People in my area with an comparible setup, average growth from this forum and to my easier SPS (monti’s, stylo’s etc).

Comparing your growth to someone else's is not a good indicator. What are your parameters? What are theirs? What are they dosing? What is their flow and lighting setup? Comparing growth of more difficult, slower growing SPS to easier, faster growing SPS is also a non-starter for obvious reasons.

A good "ballpark" PAR range for SPS is 200-350. Yes, there are people growing sticks in 600 PAR, but that typically also includes having flow and water chemistry dialed in as well. It's not just light, or just flow or just chemistry with SPS. You have to find a good balance of all three. You can run silly high PAR, but you'd better make sure your flow and water quality are on point as well.

We could debate light spectrums and the importance of red/green/white all day. Big coral farms that grow coral for a living use the whites/reds/greens for at least a period of the day, and that's good enough for me.

The AI Prime is actually a pretty solid light, but does have some issues with lens melt. If you're not comfortable running the light at the levels it needs to be running (get those violet channels turned up) for fear of melting a lens, then absolutely switch to something else. If you just want something else, then switch. Just know that if your corals are being "held back" by something, it might not be the lighting.

Like @rtparty said, I feel like the Nicrew HyperReef Gen 2 is probably the best budget light option out there right now, and a single 150w should be more than adequate for your tank.

 

[BeanAnimal]

Comparing your growth to someone else's is not a good indicator. What are your parameters? What are theirs? What are they dosing? What is their flow and lighting setup? Comparing growth of more difficult, slower growing SPS to easier, faster growing SPS is also a non-starter for obvious reasons.

But somehow comparing PAR is?
Not directed at you, but rather the general conversation.

Even though most things in the tank are great, 200-250 PAR is too low for SPS, especially long term. The hardest choice is another prime I can get for 100, or sell my primes for 200 and spend another +-400 for a Radion.

Why is it too low?

We could debate light spectrums and the importance of red/green/white all day. Big coral farms that grow coral for a living use the whites/reds/greens for at least a period of the day, and that's good enough for me.

Combine the two thoughts above. OP has "bad PAR" he thinks and is leaning toward a specific spectrum that he likes. PAR becomes rather useless. We don't need to debate spectrum, but rather understand that it drastically affects PAR readings.

First, I’ve noticed that my PAR readings are actually lower when flow is turned off. That seems counterintuitive to me. I do have a lot of surface agitation—could that be affecting the readings?

While I am not a fan of measuring at all. Why measure with flow off? What does that mean? Coral don't sit in water with the flow off, so even if the PAR was 100% higher, why measure in that state? I can tell you why. Because poorly reasoned conventional wisdom says that is what you should do.

Would adding a third Prime make a meaningful difference? Right now I have two lights spaced evenly, but I could reposition them and add a third in the center. My goal is to reach at least ~350 PAR.

Ignoring the PAR -- if you feel that you need more light, then yes adding a 3rd fixture would provide ~30% more light.

My acros have decent coloration, but growth has been very slow for most of them. I didn’t realize this might be a lighting issue until I started measuring PAR.

There can be any number of reasons. More light typically means more growth, up and until the amount of light becomes detrimental. That will vary by coral and tank.

If a third Prime won’t significantly improve things, I’m considering selling them and switching to something like a Radion instead.

Thanks!

I am not a fan of the AI lights, but they (within reason) have roughly the same output as any similar wattage modern fixture with similar emitter count. Because all of them have slightly different spectral output and you further customize to what you like, PAR is rather useless metric to compare them.