What's Your Lowest Successful PAR Level?

[kennedpa]

It does make you think when you see these facilities with all their lights feet above the tanks. The PAR cant be very high at all at these heights, but they grow.

Agreed. One caveat is their water depth which is usually 12" or less, not considering if they're mounted or already branched up, but very valid point. I know one particular place their sps gets 350 par roughly with their water depth of 10-12" and at the height they use their 250w halides with reefbrites.

 

[erk]

I have a diy led/T5 fixture above my 40B. Two lumia 5.2s with six 2ft bulbs. My par levels range from about 250-300 at the sps rock platform to 50-100 on the sandbed. The light is suspended 10inches above the water. It was originally higher, around 12inches, then lowered slowly. Since lowering, the corals -- sps, lps, and softies-- are producing brighter more vivid colors. Before they were growing slowly with decent coloring. The most impressive growth I've observed is from an acan. It's always been in low light areas, but had explosive growth, possibly because I feed it several times a week. Since I lowered the light, the coloring has changed. It was green before, but starting to get white and orange striping with higher light intensity.

 

[Makers Marc]

Since I have ruled out salinity, temperature, parameters and flow, and your running higher intensity in a shallower tank, I concluded that there must be something I missed. On a hunch I pulled out my TLF veggie clip, replaced it with a new one and pulled the back off the old one. The neo magnet on the old clip had minor corrosion on the surface. Time for some Cuprisorb. Sigh. Guess I better check any other magnets on frag racks, etc.

Sorry for the OT post, but just wanted to follow up for users who might run across a similar situation.

Dennis

Dennis,

You just laid out, an almost identical scenario my tank is going through now.

I've thought for months previously that my AP700s were burning my acros and corals, maxing at only 35-40%. Reason why I thought that was my alk was stable at 7.25dkh (so not alk burn) and my nutrients were sufficient at no3= 16ppm and po4 =.03-.08, so it had to be light acclimation to the ap700s "spectrum ", but not par per se'.

Then I saw @Dana Riddle 's par chart on advanced aquarist at 100% on spectrum 2, and thought there is no way this light can burn at 40%.. so i ordered a triton icp test.

Test came back high in Tin(Sn) at 16 micrograms/l. Found a rusty magnet and have run Cuprisorb the past 2 wks and did 40% water change over 2 days.

Now to today. I got the Apogee 510 from BRS for rent, and was stunned how low my par was across the board with lights mounted 12 in inches from water.

Question for anyone who can help or is still reading...

1. Frags I put in last week supposedly came from tanks with LED and par btw 200-300. Now they are sitting in my tank at 100 only for the past 8 days.

Would it be fine to just up my lights to 200+ par, considering that's where they were just one week ago? Dana?

Or is it best to now raise slowly like 10% per wk?



Then I realized