I think my LEDs are slowing killing my tank

[Bige]

Before LEDs the tank was spreading like crazy. I was selling weekly to lfs. Got new LEDs and growth has stopped. I have a biocube 29 with a 20 g refugium. Tunze skimmer and mp 10. I turned light time down to only 6 hours a day. Shrooms are all retracted as are zoa. All sps bleached out and monti as well. Chalice is hiding under rock and still has color. I have a pink birds nest that is at mid level but seems ok.

Water parameters as of today
nitrate 0
ammonia 0
nitrite 0
ph 7.9 but it has been for 2 years
phosphate 0
calcium 380
alk 3.70
kh 11.8
mg 1000


This about what water usually tests. Only real change was lights in feb.

 

[mr_X]

too much light too soon. how did you acclimate your tank to the new light?
i like to do the window screen method:
3 or 4 window screens in between the tank and the fixture, and remove one every few days/week or so until they are gone.

i had a similar problem when i used carbon in the tank i maintain. the water change water was always yellow, so i used carbon for a few days. the water was crystal clear, but then the light was able to penetrate easier and i lost a small acropora colony as a result.

what fixture are you using? is it dimmable?

 

[Bige]

It is the older version of nanotuners 5.6 LED retrofit. So they are not dimmable. I did use the screen technique for 3 weeks. I have reduced the time that tank receives full light. It gets mix of blue and white for 12 hours and full whites for about 6 hours. So it has dawn 3 hours, full lights for 6 hours, then 3 hours of dusk.

 

[mr_X]

it says it's comparable to a 150 watt halide, but they don't give PAR readings. a 150 isn't a ton of light over a 29 gallon IME. i have used 250 watt halides over 12" deep tanks and haven't had trouble.
the sps bleaching says it's light though. i would try running strictly blues for a couple weeks and see what happens.

 

[Bige]

I will try that. Thanks for taking the time to look that up.

 

[ryshark]

I agree, too much light too quickly. I put LEDs over the middle 1/3 of my tank over a month ago and I am still acclimating, ive been increasing the lights minutes each day, starting out at 3-hours. So far, the minimal amount of coral I have under the LEDs is looking good. (my situation is a little different because the 1/3 with the LEDs gets a little bit of halide light too from the halides on the sides.
IMO 12-total hours of light is not needed in our tanks. Consider cutting back to 8-10 total hours... maybe some time off the long dawn/dusk you have setup.
On a side note, I'd raise my Mg a little if I were you.

 

[Bige]

Alright. Today is water change so I will make some timer changes too. So should I just do 8 hours total? Skip dawn/dusk? . Mg will get increase after water change and test. What should I shoot for? Thanks for ya'lls help. I have been so frustrated.

 

[ryshark]

Alright. Today is water change so I will make some timer changes too. So should I just do 8 hours total? Skip dawn/dusk? . Mg will get increase after water change and test. What should I shoot for? Thanks for ya'lls help. I have been so frustrated.

I do 1-hour dawn, 6-hours ON, 1-hour dusk for a total of 8-hours which 6-of those 8-hours are at full light...but thats just me. You can reference how my corals are doing with that lighting schedule from my build thread. There are some recent pics on the last few pages.
I like my Mg to be around 1300-1400.

 

[Bige]

So my lfs let me borrow their milwaukee lux meter. Mine at 2inches under water measured 1900 x 10. The middle tank was 950 x 10 and bottom 300 x 10. Not sure if this means anything. Not real sure how this applies.

Comparatively. On a t5 tank 2 inches down it was 500 x10. On their mh tank it was 1100 x 10.

 

[mr_X]

i am quoting someone else and can't be sure of the validity of this statement, but:
"I have a Lux meter, and it's come in mighty handy, but if I new then what I know now I would have gladly spent the extra $100 and went with the Par meter.
Lux is basically Visable light, heavily weighted toward the green spectrum (what we see).
Par is Photosynthetically active radiation (I think it might be "Available") anyway, basically it's light that coral or plants can use for the process of photosynthsys. This includes little of the green specturm because it's not super usefull to our coral."

 

[ryshark]

I can't be sure about the validity of this either, but I think with LEDs the Lumens is more important than the PAR.