Gas exchange in skimmerless tank...

JBKReef · Mar 12, 2019

I have a 25 lagoon. Build thread in comments.

Due to a small bioload, and only housing soft corals (shrooms and zoa’s) I decided to not run a skimmer.

While the tank was going through the early stages of the ugly phase I added a few test corals. Which seemed healthy enough, so I brought on a whole load.

Things looked great for about 2 months, then all zoa’s within a week closed up and began to lose color. At this same time I was having a cyano outbreak.

I was wondering if the abundance of cyano, matched with lower gas exhange sithout a slimmer compounded my problem by removing O2 from the water.

For those without a skimmer how do you promote gas exchange?

All my corals have recovered excluding some AOI’s however I would say they are 80% back to their full glory.

Thanks for your input! And as always happy reefing.

brandon429 · Mar 12, 2019

Gas exchange not the issue here in my opinion nor for initial coral decline. We have twenty page threads on cyano cures and didn't arrive at that as a causative. Some people just adjust N or P levels to control cyano, there are also feeding and water change regimens possible that will make your corals grow fine, this current approach didn't select well for zos initially nor against cyano in the current arrangement but if it rebounded that's fine

All we do to curb that down phase in our cyano cure threads is be hands on, vs hands off when the tank is new. We clean out all invaders and never let them compile, while feeding each coral targeted with certain reef feeds plus higher water changes. We only back off later on, as the tank matures, and we run mostly blue light as whites will stress and bleach. Your tank is open topped, low bioload and not organically packed so the gas exchange can't be off imo. The chemical test if you want to assess gas exchange is the bubbled sample cup of water for pH-carbonic acid buildup from lack of exchange, pre and post sample bubbling (which evacuates any co2 then the ph tests higher post bubbling)

If your samples test the same pH pre and post bubbling then gas exchange is ok

JBKReef · Mar 12, 2019

I was just curious... while reading a thread earlier ragarding sick fish @Humblefish mentioned bacteria blooms decreasing O2 availability and potentially harming fish.

I just wondered if not running a skimmer and not much surface agitation would result in the same.

Additionally I was worried about too large of water changes due to stripping all nitrates and phosphates out of the water. Was measuring 0 Nitrate, and 0.0 phosphate. (Nitrate - Red Sea Test, Phosphate Hanna checker)