Cerameco Vida Rock Observation & Question

[broodc2]

So my tank is now almost a year old. I'm struggling with GHA currently but it isn't your normal breakout. I've been fighting this for about 2 months now. The interesting thing is, the GHA only grows on my Vida Rock pieces and my live rock is completely clean and has coralline encrusting. I can't figure it out. Cerameco claims that the rock does not leach phosphates so I'm wondering what is causing this phenomenon. I test phosphates with Hanna checker and get a reading of zero. Nitrates are at around 1.5. I do regular 20% weekly water changes. I use RO/DI. I don't have a silicate test so that is the only thing I'm not 100% of. But I haven't had any sign of diatoms for about 6 months.

For the life of me I can't figure out why the GHA is only growing on their rocks, but not on my live rock. I suppose if I was overfeeding/under skimming, etc. the GHA would be growing everywhere correct? Does anyone else have an experience similar to me? Here are the things I've eliminated as causes:

• I observe my CUC and they don't show a particular preference to the live rock versus the vida rock. I've tried manually placing hermits, snails, even my fighting conch on both live rock pieces and vida rock and don't notice them scurrying off one or the other or otherwise giving preference to one rock over the other
• If you break my tank into 6 sectors (i.e. top left, top center, top right, bottom right, bottom center, bottom left) I have both vida rock and live rock in all 6 sectors so I have to think flow and/or lighting isn't the cause.
• As an experiment I chipped off a piece of the surface on a portion of the vida rock, exposing the white ceramic in an attempt to see if it's the purple coloring on the surface that is leaching something. I just did this though so there hasn't been sufficient time to see if algae grows on the exposed part just yet. I assume the claim of not leaching is applicable to the vida rock material AS WELL AS the purple painted coating. We will see.

This is really frustrating because I was skeptical of any man made rock leaching but had heard and was told vida rock doesn't leach. Anyone have any other thoughts or similar experiences?

 

[ERIC1975]

Yeah I have the same problem. I bought a large piece of Cerameco rock structure at RAP last and it's been in my tank for over 7 months and I still have GHA growing on it but no where else in my tank. My Po4 is 0 and nitrate is 0.2. I'm pretty sure that Cerameco rock is leaking something that's feeding the algae....

 

[BAUCE]

Pretty sure it's leaching silicates. I have the same rock and my algae is currently under control after 4 months. Others have claimed it was silicates if you search around.

 

[Eckolancer]

I have their rock and only place algae even thinks about growing if at all is on my glass. Had the rock for about a year as well. When I first got the rock it just went through the normal stages of dead rock. You know little algae then coraline. BTW my whole tank is only cerameco rock. Only thing that has any real live rock to it was the frags I bought from others. So less then a handful of live rock in my tank as well as sandless. Finally got my dosing under control and phosphates to near 0 that sps is starting to take off.