Approximating and Maintaining Water Chemistry of a Meromictic Lake

[rhizotron]

I'm not sure why you are starting using CaCO3 in a mix intended to dissolve since it has quite low solubility. If you feel you want carbonate, I think you'd be better off using potassium or sodium carbonate.

Please see the spreadsheet above. I'm trying to get the ion concentrations close to the target values. LIke I mentioned, this updated blend had very little sediment. Actually, the extra 8-liter batch I have had in this jug for a couple weeks is now completely clear.

If calcium carbonate is near saturation that should advance the goal of getting precipitation on the reef structure rock surfaces where the photosynthetic microorganisms are growing.

 

[rhizotron]

I finally got around to some more microscopy. I think everything here is new growth since the tank has been set up with the Green Lake samples. My economy brightfield microscope is OK for viewing these pigmented photosynthetic organisms. This was 1000X, with some cropping.

Filamentous Cyanobacteria and benthic Diatoms are present. I believe the darker green oval shapes to be the benthic Synechococcus Cyanobacteria implicated in the lake reef formation and I'm pleased to see them in there!

At much lower magnification I also got a view of the developing filamentous Green Alga. I would be interested to hear if anybody might know ID for this one.

 

[rhizotron]

This took me forever but I've finally made some progress with the display tank. I spent hours looking at rocks on the Internet and over by the lake, then it occurred to me to try a local landscaping supplier where I found this really nicely contoured sandstone outcrop slab.

I think this is prefect. Here's one of the shots of Deadman's Point in Green Lake from the collection day in September. You can't see much of the microbialite reef structure, but it visible as a shallow ledge projecting out into the lake.

I hope I might get a chance to snorkel there one day to see the reef and get some additional underwater photos.

Tank with water and aragonite sand.

I really like this shallow 24" X 24" frag tank configuration. This is only about 16 gallons, basically a nano tank, but the broad footprint creates the impression of a much more expansive setup and it provides this excellent view from above.

Lastly here's a day-72 update for the culture tank. I haven't poked at it too much, but it definitely looks as though a CaCO3 crust is developing with the Synechococcus Cyanobacteria and benthic Diatoms growing on the beer bottle. Also present are two different filamentous Green Algae.

 

[rhizotron]

For anybody interested I started a journal discussion for the preliminary tank setup and here's the link:

https://www.reef2reef.com/threads/g...ater-microbialite-reef.1022002/#post-11980675

I'll be back here if I have additional water chemistry questions, which I'm sure I will.

 

[Randy Holmes-Farley]

Thanks for the link!

 

[rhizotron]

I got the live material into the display tank. There are some more microscope images and other details over in my journal thread, but here's a few water chemistry observations.

It took a few days and I also injected CO2, but I got almost all of the salt mix dissolved into 15 gallons of water to fill the tank. There has been no obvious precipitation and for several days TDS has stayed at right around 700.

Here's the beer bottle after I scraped pieces of the periphyton into the display. I think there's pretty clear precipitation of new CaCO3 crust here. And it has happened pretty fast.

I used little limestone chips to hold the pieces down on the sandstone slab while the organisms hopefull establish.

Magnified images of the periphyton right from the culture tank appear to show substantial calcite crystal development right around the Cyanobacteria and Green Algae filaments.