Realistic par for frag/grow out tank!?!? Help!

Salty-Sailor · Jul 28, 2017

Just to get right to it I'm trying to figure out what is a good par for my frag tank/grow out tank.

I finally was able to get a par meter to borrow and found out my par levels were way below what I thought I was getting! Surprise! Lol

All my LPS and soft corals are fine with what seems to be any par throughout the tank but acro's up top on bonsai reef frag rack seem like they want MORE!

Now to get to some specifics!

Tank is an odd acrylic tank 32in x 30in x 14in

Bonsai rack brings acro's 5inch down from the surface of the water.

Lights are 2x radion gen4 pro xr15's at 12in above the surface of the water as well as I've been running a 4 bulb t5 24in fixture at an angle for 1 hour mid day for a little extra punch.

*Disclaimer don't judge me*

Par on average on acro's is 65-75 par and when t5 on just slightly higher.

Now let me have it guys! Suggestions???

Gweeds1980 · Jul 28, 2017

Are you sure the par meter is right? I've seen some independent test on the g4 pro which gives par readings of 160 at the bottom of an 18" deep tank, with the light mounted 8" above the surface... not sure how you're reading 100 less par at much less depth?

The tests were running the lights at 100% on all channels... I'd suggest turning them up before you change or add more lighting... even if the colour isn't to your liking, remember it's a frag grow out tank so more about the growth than the aesthetics.

Dana Riddle · Jul 28, 2017

A PAR value of 300 - 400 should maximize photosynthesis in most Acropora species (lower for some of the deeper water bottlebrush types.) I generally recommend a minimum PAR of 100, although it is certainly possible to get by with less.

Salty-Sailor · Jul 29, 2017

Gweeds1980 said:
Are you sure the par meter is right? I've seen some independent test on the g4 pro which gives par readings of 160 at the bottom of an 18" deep tank, with the light mounted 8" above the surface... not sure how you're reading 100 less par at much less depth?

The tests were running the lights at 100% on all channels... I'd suggest turning them up before you change or add more lighting... even if the colour isn't to your liking, remember it's a frag grow out tank so more about the growth than the aesthetics.

One thing i did not specify was the fact that im running a schedule sent to me by my LFS with some of the best acropora well known in my area but running originally at 30% overall which intensity was around 20% maximum and now im running overall 40% with maximum intensity at 25/26%

the plan is to raise the overall level 5% every 5days so i dont shock any corals with to much light intensity change. my only thought is how long do i increase? at what par should i realistically be happy with and stop?

Salty-Sailor · Jul 29, 2017

Dana Riddle said:
A PAR value of 300 - 400 should maximize photosynthesis in most Acropora species (lower for some of the deeper water bottlebrush types.) I generally recommend a minimum PAR of 100, although it is certainly possible to get by with less.

awesome! i appreciate the input! im going to start raising my overall intensity over the course of august and see where i get at the end of that month.

Thanks!