Yup there are many views on Coralline algae and for the record i do not particularly like a tank covered in it. But because i do not like the look does not mean that it is a no no, or detrimental to your live rock. I have many systems with various degrees of propagation and cannot say that any ones LR filtering is better or worse than the other due to Coraline. I have picked one system that is densely propagated and will comment here on. First some PIC's
This particular tank is 3000mm(l) x 450mm(w) x 650mm(h) +- 900l with all sump and overflows considered. Circulation is by means of 4 seio pumps (i can't rem off hand the models). Filtration is simple. Overflow to sump with BIO balls and ceramic rings to a division for the one Jagger 300w heater to a DSB (the dsb is purely a 150mm sand bed with no light chito etc) then return. A deltec apf600 does the skimming and a PO4 reactor with rowa does it's thing. Lights are 6x 80w Aquablue+ & 2 x 80w Actinic+ T5.
The tank has no SPS or LPS but houses a number of softies and an anemone. Fish are nothing special other than a dory and a navarchusthat keeps the aiptaiser at bay.
A Water change of 100l is done once a month. and the salt used is tropic marine pro reef. NO Calcium, iodine, strontium, marine snow or additives are used. The only thing feed is frozen foods for the fish.
Over the past 4+ years, Nitrates hover between 5 & 10ppm and PO4 between 0,008 & 0,015.
Considering this example and others that we maintain no alarming effect or damage can be observed to the LR. I Take it from Bob the (reef) builder's post he experiences the same as we do.
From a viewpoint as to what coralline on LR looks like in it's natural habitat one only has to observe the LR as it is made available from the retailers. Some LR like the Kenya LR is sold as Kenya Red or Kenya Green, depicting the colour of coralline or algae. The Sri Lankan LR is also reasonably covered in coralline. I must admit that as a fairly new diver i did not at first notice coralline algae in abundance on the reef, concurring what JB says. However it was pointed out to me that the reason is because, one needs to put a red filter on ones mask or shine a bright light on the reef to see the coralline. I will check if this is so on my next dive.
So my view is coralline is OK if it blows your hair back. And i believe it does not have a dramatic effect on LR filtering capabilities. It will not stop Bryopsis or Valonia from growing and it does make a tank apear clean.
Does it eat up all your calcium? Hmmm.... not sure, as the example tank is not dosed kalkwasser or calcium in any form and the ca remains a steady 424ppm, KH6 & pH 8.0-8.1 So the only source of ca can come from the salt water, LR or calcite substrate.
