Optimal PAR Readings with LED Lights
- Thread starter webdizzy
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AdamSabina
New member
It's usually a little opinion and science. Mine is that. SPS 250-450 (I'd start with under 250 and go up). LPS and softies 50-200 (start low also).
AdamSabina
New member
It's not that they aren't dependable, it's that they don't accurately measure certain wavelengths. They can be as much as 30-40% low at 400 nm.
If you've noticed bleaching, the lights need turned down. Increasing flow could also help, as water movement plays a role in how much light is required prior to reaching photoinhibition.
webdizzy
New member
I did turn them down. Way down. They're now at just a bit more than 25% strength and I'm still seeing bleaching. I'd really like the tank to be brighter but I need to see what the par readings are so I can rule out the lights being the problem and before I turn them up. I've also been having some trouble keeping nitrates down, but I think I've got that turned around now so just need to get the lighting right.
Without knowing your previous measurements the PAR meter won't help much but it is a valuable tool. At this point I would base it off the bleaching. It seems, anecdotally anyway, that running your white channel too high is more likely to cause bleaching. The damage can happen in days but it can take weeks, or months, to see improvement. When you get the meter make sure you have at least 50 PAR on the sandbed. Corals can tolerate low light conditions better than high light conditions and browning is far easier to reverse than bleaching. I wouldn't increase intensity until the bleaching had stopped and I saw imorovement for several weeks.
Looking at your water parameters is important. The corals are stressed and they will need stability to recover. If changing lighting coincided with the bleaching I would lean towards that being the cause though.
Looking at your water parameters is important. The corals are stressed and they will need stability to recover. If changing lighting coincided with the bleaching I would lean towards that being the cause though.
This is true as well. Higher nutrients can also increase the point at which photoinhibition occurs.
AdamSabina
New member
+1. Some have issues at the upper 780nm range (red). This isn't really an issue though because if you looking for 250-450PAR. If you have 300 even with a 20% error your fine. It just a number to help you know which side to error on. If one setting on you lights is 300 par and the other is 200. The first is brighter. Also if you see 1400 par like what IS possible on many high end LEDs you are WAY to bright even counting a 40% error.
PAR meters are a great tool but they can only get you in the right zip code. You have to adjust based on what your corals want. If it's bleaching the tip at 150 PAR turn the light down/ find what causing it to bleach.
I stopped using LEDs about a year ago after trying several high end units and bleaching everything out no matter how much I adjusted them. I've since gone back to T5. The only LED I would consider using is a Pacific Sun because they don't use white LEDs. Read the thread "open letter to the LED industry." White LEDs will grow coral for a short bit but are harmful in the long run.
I believe the current TOTM would beg to differ.
White leds have not been proven to be definitely harmful to corals, only reduce their colors.PAR wise, get 100 on the sandbed and go up from there.
Ron Reefman
Active member
White leds are less useful to coral, not harmful unless over exposed. And any spectrum of light that a coral is over exposed to, including blue, will also cause problems.
Given you tried several high end led fixtures and had problems with all of them, and yet SO MANY here use both high end and Chinese economy led fixtures and have wonderful sps & lps growth tells me it wasn't the leds that were your problem. Why are 98% of us doing just fine with leds (and with white leds included) if they are the problem? Just because you had problems doesn't mean white leds are the problem.
Ron Reefman
Active member
Well, early led fixtures did have a lot of problems. First they were only white leds and no dimmers, then they added some blue (not enough and no variety and still no dimmers, then more blues and finally dimmers, at which point they became worth owning. But it's still not hard to bleach corals if you aren't careful.
I switched all 4 of my tanks to all leds 9 months ago and wouldn't consider going back to MH.
I switched all 4 of my tanks to all leds 9 months ago and wouldn't consider going back to MH.
AdamSabina
New member
Which LEDS are you using and which PAR meter?
If water parameters are off you'll likely see bleaching on all sides not just tips. As for which water parameter most can do it but Alk is my usual suspect.
webdizzy
New member
I have two Cree fixtures on a 75 gal. The par meter is an Apogee Quantum Flux MQ-200.
The bleaching is all over; not just tips.
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