Par needed for a LTA?

el aguila · Oct 13, 2016

I have a spot at the edge of my sand bed on one side of my tank that I'ld like to put an LTA. I recently checked my par in this spot and it is around 75.

My light is a DIY LED, and I can probably increase the par by increasing the LEDs over this and swapping out different optics. My question is what do I need to keep a LTA healthy?

mcarroll · Oct 14, 2016

They seem to be as capable in "low light" as most corals, so anything over 10,000-15,000 lux. More is OK.

75 PAR is probably around 3000-5000 lux.

This is still usable light – they will consume physical food and dissolved nutrients in the water (as available) to make up the difference. (Corals survive down to 1000 lux and I think even less under otherwise-favorable circumstances. i.e. lots of food consistently available.)

Keeping them under low light means you have to think of them more like a fish and take care of their feeding requirements consciously. Either there need to be plenty of nitrates and phosphates in the water, or you have to do some hand feedings.

In contrast, anemones in well-lit tanks that have plenty of dissolved nutrients never need to "eat" like we normally thing of it: chunks of fish or meat. A friend has a tank with hundreds of LTA's that never get an ounce of attention. They just keep reproducing on light and fish poo/pee. LOL.

I think there may be a general rule that in a tank that gets plenty of light and plenty of dissolved nutrients, corals/polyps don't need to be directly "fed" by us.

Salty1962 · Oct 15, 2016

+1 on the feeding at that PAR. The trick is getting it to stay there, I know they don't move much but they will if the area isn't to it's liking.

el aguila · Oct 17, 2016

I'm going to bunch up 5 LEDs (1-RB, 1-WW, 1-B, 1-CW, 1-RB) with small optics to punch the light through 27" of water. I would hope that I could get a par of 100 in this spot. Presently there are 2 RBs over this spot that don't have tight optics more for color rather than par.

I don't want the LTA to start moving because it isn't getting enough light.

I have Caribe reef floor sand which is probably too coarse, so I've buried a 3" wide PVC pipe about 2" tall in the sand bed and filled it with Southdown Play sand.

I'll have to wait for about a month to rework the lights, and then I'll start looking for a nice LTA>