newbie with a couple of questions!

[gistsc]

I am very new to the marine hobby, and I have recently notice some things in my tank that I wanted to know about. First, my substrate (2" deep crushed coral) has been slowly turning dark purple. I am assuming it is a type of algae, and wanted to know if it was good or bad? My crabs seem to be content eating it. In conjunction with the purple algae, I have notice small bubbles forming on the substrate that grow and break loose then rise to the top. Is this normal? both of these events started after upgrading from 80w standard floresent stet up to 384w compacts

Thanks in advance for any help.

[Shagsbeard]

Pictures would help a lot. Information about the tank would help even more.

How long has the tank been running? New tanks go through periods of rapid algae growth (blooms) as part of them finding their equilibrium. It could be diatoms, but most people describe it as brown, not purple.

The bubbles forming in the substrate are normal Nitrogen. Nitrates are being turned into nitrogen gas by anaerobic bacteria... very good sign. If you get some critters that move sand about this air will be released. Many gobies do the job well, as well as nassarius snails and other inverts.

[bertoni]

The bubbles might be nitrogen, but I suspect they're oxygen from photosynthesis. Is the purple film rock-like, or does it break up easily when touched?

Crushed coral tends to collect detritus unless cleaned regularly and thoroughly. I ditched mine, but it will work as a substrate with some attention.

[troybob333]

It is just an algea out break from the new a lot more powerfull lights. Purple does sound a bit weird though but I'm guessing it is diatom. Low flow can be part of the problem letting the diatoms grow. What do you have for flow and what size of tank?

[showtime305]

What about cyno? Cyno can be a dark plum color.

[gistsc]

Thanks for the quick responses. To help in figuring out what this is, I will try to give a little more info. I inherited the tank a couple of months ago. It was originally a fish only tank that was overstocked, and the water quality was poor. I have added 60 lbs of figi live rock, the new lights, and lots of helpers. Roughly 20 zebra crabs, and 30 turbo snails. As for fish, I still have all the fish, three damsels, two engineer gobbies, and one starry blennie. I fixed the water quality just after setting the tank back up. Salinity is 1.024, and ph 7.8 at night, and 8.0 late in the day after lights have been on for about 12 hours. Ammonia is 0, nitrites 0 and nitrates 20. Calcium levels have been at or above 400. My next planned step was to replace the external canister filter with a sump and add protein skimmer. I would also be open to any suggestions on continuing upgrades. I am working on a tight budget, so I can only do one good upgrade a month. Sorry I can not take pics, I do not have a digital cam. I will try to borrow one.

Thanks again.