Approximating and Maintaining Water Chemistry of a Meromictic Lake

[rhizotron]

Approximating and Maintaining Water Chemistry of a Meromictic Lake

I'm starting a new project as a continuation of my Stromatolite Reef setup maintained with hypersaline (85ppt) water and 2-part calcium + alkalinity dosing for biologically-mediated precipitation of CaCO3 and stromatolite development.

The next tank I'm planning will attempt to model the fascinating system of Green Lake, New York. a small, but very deep lake near Syracuse. Green Lake is a meromictic lake, with its distinct and permanent water level stratification maintained by its depth, steep sides and the influx of saline water via deep underwater springs.

(Source: Brunskill, G. J. Ludlam, S. D., (1969), FAYETTEVILLE GREEN LAKE, NEW YORK. I. PHYSICAL AND CHEMICAL LIMNOLOGY, Limnology and Oceanography, 14, doi: 10.4319/lo.1969.14.6.0817.)

Among other fascinating features of Green Lake is the thrombolite reef structure at Dead Man's Point on the lake's eastern shore. I intend to model this an a living aquarium aquascape.

(Creative Commons image: https://en.wikipedia.org/wiki/Green_Lake_(New_York)#/media/File:GreenLakesDeadmanPoint.jpg)

I'm no chemist, so I could use some help with a starting point for approximating Green Lake's water chemistry, especially the high calcium and bicarbonate concentration that supports the microbial thrombolite development. Here's a table from the Brunskill and Ludlam paper (also shown above) with ion concentrations as measured almost fifty years ago. I'm most interested in conditions at shallower depths and above the level of the chemocline, so see the table below for the values highlighted in yellow. Apparently the lake ecosystem has been maintained in a more or less healthy and stable condition in recent years, so these would not be expected to have changed much.

(Source: Brunskill, G. J. Ludlam, S. D., (1969), FAYETTEVILLE GREEN LAKE, NEW YORK. I. PHYSICAL AND CHEMICAL LIMNOLOGY, Limnology and Oceanography, 14, doi: 10.4319/lo.1969.14.6.0817.)

Green Lake is surprisingly salty for an inland lake. Groundwater flux from the Silurian marine shales, dolomites and other rock layers account for the elevated sulfate, sodium and chloride levels.

Do any readers here have tips or ideas for approximating and maintaining this chemistry? If I can get the organisms to grow, they will deplete calcium and alkalinty, so I also need a plan for replenishment. The aquarium I have in mind os just ten gallons, so a 2-part dosing regime should be acceptable for maintenence. Could an off-the-shelf 2-part be acceptable, or will I have to mix up my own salts?

I think that trace mineral concentrations are less critical. I don't intend to dose for those and I should be able to maintain growth of the Cyanobacteria and associated thrombolite organisms with occasional guesstimated dosing of BG-11 or other nutrient medium solution.

Thanks for reading. Like I mentioned I do't have a lot of practice with water chemistry, so any hints, shortcuts or explanations would be greatly appreciated.

 

[KrisReef]

Interesting. I am not the chemist who can help you out with the details. The elements are not just a simple concentrate of hobby salts for marine applications. Looks like the main ingredient is Calcium Sulfate but as mentioned before this is not my expertise. If I were going to do this I’d probably try and find a way to get a few 55 gallon barrels of actual lake water to avoid having to do the chemistry calculations that I’d struggle to get right.
I use natural sea water from Scripps in San Diego and add alk and Mg to get the mixture I need at home. GL!

 

[rhizotron]

Interesting. I am not the chemist who can help you out with the details. The elements are not just a simple concentrate of hobby salts for marine applications. Looks like the main ingredient is Calcium Sulfate but as mentioned before this is not my expertise. If I were going to do this I’d probably try and find a way to get a few 55 gallon barrels of actual lake water to avoid having to do the chemistry calculations that I’d struggle to get right.
I use natural sea water from Scripps in San Diego and add alk and Mg to get the mixture I need at home. GL!

Thanks for reading! Yeah I don't imagine this will work with a reef tank 2-part, but I hope that I can figure something out with some other combination of a few salts. The major ions here are calcium, magnesium, bicarbonate, sodium, chloride and maybe potassium. The lake is 850 miles from here, so scooping water for tank filling is not really viable.

I might leave this aquarium as a strictly microbial, or I might add a light load of hardwater-adaptable nano fish, such as Dalmation Gambusia or Heterandria formosa. A few fish will help with a steady input of ammonium, phosphate and more for feeding the microbes.

A friend of mine is collecting, with permission, a small sediment sample and a water sample from the vicinity of the microbialites in Green Lake. I hope I can get the microbes to grow. Green Lake is known for its unique and high microbial diversity, but it is apparently benthic Synechoccus Cyanobacteria implicated in most of the precipitation of calcium carbonate and reef/marl formation. I'm keeping this tank in a room in the house apart from any other freshwater setups in order to minimize introduction of common aquarium algae and microbes including any that might be more aggressive than the Green Lake flora. Actually with this idea mind it might be best to avoid adding any fish, at least during the early tank establishment.

 

[TangerineSpeedo]

I use natural sea water from Scripps in San Diego and add alk and Mg to get the mixture I need at home. GL!

Ooh... Fancy pants... Too good to scramble down the rocks at the inlet with three 5 gallon jugs at high tide...?

 

[TangerineSpeedo]

Approximating and Maintaining Water Chemistry of a Meromictic Lake

I'm starting a new project as a continuation of my Stromatolite Reef setup maintained with hypersaline (85ppt) water and 2-part calcium + alkalinity dosing for biologically-mediated precipitation of CaCO3 and stromatolite development.

The next tank I'm planning will attempt to model the fascinating system of Green Lake, New York. a small, but very deep lake near Syracuse. Green Lake is a meromictic lake, with its distinct and permanent water level stratification maintained by its depth, steep sides and the influx of saline water via deep underwater springs.

(Source: Brunskill, G. J. Ludlam, S. D., (1969), FAYETTEVILLE GREEN LAKE, NEW YORK. I. PHYSICAL AND CHEMICAL LIMNOLOGY, Limnology and Oceanography, 14, doi: 10.4319/lo.1969.14.6.0817.)

Among other fascinating features of Green Lake is the thrombolite reef structure at Dead Man's Point on the lake's eastern shore. I intend to model this an a living aquarium aquascape.

(Creative Commons image: https://en.wikipedia.org/wiki/Green_Lake_(New_York)#/media/File:GreenLakesDeadmanPoint.jpg)

I'm no chemist, so I could use some help with a starting point for approximating Green Lake's water chemistry, especially the high calcium and bicarbonate concentration that supports the microbial thrombolite development. Here's a table from the Brunskill and Ludlam paper (also shown above) with ion concentrations as measured almost fifty years ago. I'm most interested in conditions at shallower depths and above the level of the chemocline, so see the table below for the values highlighted in yellow. Apparently the lake ecosystem has been maintained in a more or less healthy and stable condition in recent years, so these would not be expected to have changed much.

(Source: Brunskill, G. J. Ludlam, S. D., (1969), FAYETTEVILLE GREEN LAKE, NEW YORK. I. PHYSICAL AND CHEMICAL LIMNOLOGY, Limnology and Oceanography, 14, doi: 10.4319/lo.1969.14.6.0817.)

Green Lake is surprisingly salty for an inland lake. Groundwater flux from the Silurian marine shales, dolomites and other rock layers account for the elevated sulfate, sodium and chloride levels.

Do any readers here have tips or ideas for approximating and maintaining this chemistry? If I can get the organisms to grow, they will deplete calcium and alkalinty, so I also need a plan for replenishment. The aquarium I have in mind os just ten gallons, so a 2-part dosing regime should be acceptable for maintenence. Could an off-the-shelf 2-part be acceptable, or will I have to mix up my own salts?

I think that trace mineral concentrations are less critical. I don't intend to dose for those and I should be able to maintain growth of the Cyanobacteria and associated thrombolite organisms with occasional guesstimated dosing of BG-11 or other nutrient medium solution.

Thanks for reading. Like I mentioned I do't have a lot of practice with water chemistry, so any hints, shortcuts or explanations would be greatly appreciated.

You take MTS to a whole new level... I thought I was being clever with my surge tide pool tank

 

[Gumbies R Us]

Following along!

 

[KrisReef]

Ooh... Fancy pants... Too good to scramble down the rocks at the inlet with three 5 gallon jugs at high tide...?

Of course it is as you said, I am “too good”for almost everything else too.

A long time ago I moved a 125 or two up north and I used cardboard boxes with Hefty Bags (Free endorsement!) to bring the water for the tanks to the new place. I wasn’t too good for proper containers, I was too cheap(or broke). But I found a way to keep busy with the hobby.

So, I’m not really able to haul anything off the jetty safely and I miss being able to get around like I once took it all for granted.

But, without pants or with pants I’m still happy to get source water from the source when I can. Salt mixes for the hobby are not going to help the op. I’m curious to see what solutions are available, if any for mixing up a replacement for this particular lake.

Yes,
I miss the good old days

Edit: I get 1-2 hundred gallons of NSW when I go. I stockpile it in the garage for water changes or emergency use.

 

[TangerineSpeedo]

Of course it is as you said, I am “too good”for almost everything else too.

A long time ago I moved a 125 or two up north and I used cardboard boxes with Hefty Bags (Free endorsement!) to bring the water for the tanks to the new place. I wasn’t too good for proper containers, I was too cheap(or broke). But I found a way to keep busy with the hobby.

So, I’m not really able to haul anything off the jetty safely and I miss being able to get around like I once took it all for granted.

But, without pants or with pants I’m still happy to get source water from the source when I can. Salt mixes for the hobby are not going to help the op. I’m curious to see what solutions are available, if any for mixing up a replacement for this particular lake.

Yes,
I miss the good old days

Edit: I get 1-2 hundred gallons of NSW when I go. I stockpile it in the garage for water changes or emergency use.

Yes, I have heard about the Script’s free water. If I lived closer I would partake. That is a great thing that they do.

 

[Randy Holmes-Farley]

The calcium and alk are surprisingly close to seawater, but sodium, chloride, and magnesium are much lower. I think that sets up a problem: unless the pH is quite low, rapid precipitation of calcium carbonate may result.

Do you have a lake pH measurement to use to understand the issue?

 

[LadAShark]

Thanks for reading! Yeah I don't imagine this will work with a reef tank 2-part, but I hope that I can figure something out with some other combination of a few salts. The major ions here are calcium, magnesium, bicarbonate, sodium, chloride and maybe potassium. The lake is 850 miles from here, so scooping water for tank filling is not really viable.

I might leave this aquarium as a strictly microbial, or I might add a light load of hardwater-adaptable nano fish, such as Dalmation Gambusia or Heterandria formosa. A few fish will help with a steady input of ammonium, phosphate and more for feeding the microbes.

A friend of mine is collecting, with permission, a small sediment sample and a water sample from the vicinity of the microbialites in Green Lake. I hope I can get the microbes to grow. Green Lake is known for its unique and high microbial diversity, but it is apparently benthic Synechoccus Cyanobacteria implicated in most of the precipitation of calcium carbonate and reef/marl formation. I'm keeping this tank in a room in the house apart from any other freshwater setups in order to minimize introduction of common aquarium algae and microbes including any that might be more aggressive than the Green Lake flora. Actually with this idea mind it might be best to avoid adding any fish, at least during the early tank establishment.

Meromictic Lake - an overview | ScienceDirect Topics

www.sciencedirect.com

You may have already seen this, but this may help.

 

[rhizotron]

The calcium and alk are surprisingly close to seawater, but sodium, chloride, and magnesium are much lower. I think that sets up a problem: unless the pH is quite low, rapid precipitation of calcium carbonate may result.

Do you have a lake pH measurement to use to understand the issue?

pH is pretty high...

(Source: https://ottohmuller.com/nysga2ge/Files/...pdf)

Calcium is always near saturation in Green Lake and this accounts for the seasonal whiting events there and the corresponding annual varve deposition as well as thrombolite growth. The individual Synechococcus cells function as sites for suspended calcite precipitation through through increased pH and alkalinity...

(Source: https://ottohmuller.com/nysga2ge/Files/2012...20York.pdf)

Maintaining the planktonic Synechococcus could be another cool feature of a model ecosystem. I imagine that such high calcium concentration will clog impeller pumps pretty quick, so to save on a canister filter and encourage suspended cells I might consider some kind of alternative filtration + water motion idea such as the wave tank mechanism I've been working on or the simple DC motor submerged paddle I built for this other phytoplankton tank...

 

[rhizotron]

Bookmarking some chemical compound sources...

• MgSO₄ https://www.bulkreefsupply.com/bulk-magne...ducts $29.99 for 7 pounds
• CaSO4 https://www.carolina.com/caLw_wcB $9.30 for 500 grams
• CaCO₃ https://www.midwestsupplies.com...m-carbonate $3.99 for 1 pound
• CaCl2 https://www.bulkreefsupply.com/esv-calci...oducts $16.99 for 800 grams
• NaCl (lab grade) https://www.flinnsci.com/sodiu...EALw_wcB $9.89 for 1 kilogram
• MgCl₂ https://www.carolina.c...GYaAnsBEALw_wcB $15.20 for 500 grams
• NaHCO₃ (lab grade) https://www.carolin...AgoqEALw_wcB $18.75 for 2 kilograms
• KHCO₃ https://shop.greatfermentations.c...ALw_wcB $8.49 for 1 pound

 

[laverda]

pH is pretty high...

(Source: https://ottohmuller.com/nysga2ge/Files/...pdf)

Calcium is always near saturation in Green Lake and this accounts for the seasonal whiting events there and the corresponding annual varve deposition as well as thrombolite growth. The individual Synechococcus cells function as sites for suspended calcite precipitation through through increased pH and alkalinity...

(Source: https://ottohmuller.com/nysga2ge/Files/2012...20York.pdf)

Maintaining the planktonic Synechococcus could be another cool feature of a model ecosystem. I imagine that such high calcium concentration will clog impeller pumps pretty quick, so to save on a canister filter and encourage suspended cells I might consider some kind of alternative filtration + water motion idea such as the wave tank mechanism I've been working on or the simple DC motor submerged paddle I built for this other phytoplankton tank...

I have some very old style Tunze pumps where the motor block was above the water and the pump portion hangs down below the water. I would let you have them for the cost of shipping.

 

[rhizotron]

I have some very old style Tunze pumps where the motor block was above the water and the pump portion hangs down below the water. I would let you have them for the cost of shipping.

Interesting...do you have any pics? How big are they? This is just going to be a 10-20 gallon setup.

Here's one of the tanks I'm considering...

https://buceplant.com/products/uns-60s-10-gallon-ultra-clear-rimless-aquarium

This is another idea...

https://www.thefishroom.net/products/seapora-rimless-aquarium-frag-21-gallons

 

[rhizotron]

I haven't updated this discussion in some time, but I've made some more headway with the project including an updated salt mix which I'll explain at some point. I should start a new project discussion to explain the aquarium setup with more detail.

The reef aquascape will get an updated, larger aquarium, but I've had the samples in this little 6G frag tank filled with the water blend. Aside from a few 5ml capfuls of BG-11 Cyano medium and this dim LED ring light, it hasn't gotten much attention. But the organisms are starting to grow and respond...

The state park staff would not let my friend collect any pieces of stone. But he was able to take a few sand substrate samples along with this glass beer bottle that had been in the water some time and starting to grow the characteristic CaCO3 crust. The amber color is all new growth that has developed here in the tank..

 

[Randy Holmes-Farley]

Thanks for the update. I'm interested to know what pH and alk you can maintain in this salt mix.

 

[rhizotron]

Thanks for the update. I'm interested to know what pH and alk you can maintain in this salt mix.

Thanks for stopping by!

I had gotten some other help calculating the target concentrations based on the lake field data from 1966 and here they are.

1,119ppm SO4
200ppm HCO3
420ppm Ca
72ppm Mg
34ppm Cl
17ppm Na
3ppm K
2.8ppm SiO2
1.8ppm NO3

I also have an updated version of this, but here's the spreadsheet roughly converting that to dosages for the salts I had on-hand.

Here are the amounts per liter taken from that third column.

KHCO3 - 4.8 mg/L
MgSO4 - 730 mg/L
CaSO4 - 1260 mg/L
CaCO3 - 301 mg/L
Reef Crystals - 55 mg/L

Blended for 8 liters I got almost 19 grams of mix. This is my cheap kitchen scale; I used a much more precise lab-grade scale at the shop to measure portions.

Even after mixing for several days with a powerhead in the pail this did not totally dissolve. I wanted to have some water so I could get the samples out of the fridge, so I let it settle and siphoned the clear water from the top. The sediment that I then collected and dried out amounted to about 12% of the original blend.

Here are the values I got with conversions comparing the clarified blend #1 with the fresh lake sample and our hard tapwater using the TDS meter, refractometer and cheap (API brand) titrant tests.

Actually I have an updated blend with one more salt I got (MgCO3) and I'll post that in my next response.

 

[Randy Holmes-Farley]

The precipitate is likely mostly calcium carbonate. The pH will need to be very low (meaning exposed to very high CO2 air) to keep all that dissolved.

 

[rhizotron]

The precipitate is likely mostly calcium carbonate. The pH will need to be very low (meaning exposed to very high CO2 air) to keep all that dissolved.

Yes, the CaCO3 either failing to dissolve or reprecipitating was the main problem with that blend #1. Here is the updated blend #2 including MgCO3 and omitting MgSO4.

CaSO4 - 1300 mg/L
KHCO3 - 8 mg/L
MgCO3 - 250 mg/L
CaCO3 - 95 mg/L
Reef Crystals - 60 mg/L

This is only 1/3 the amount of CaCO3 and there was very little sediment when I mixed it. The organisms seem to be growing fine in this water.

I'm wondering about a second enclosure with CO2 injection and slow water recirculation with the main display maintaining a short pH gradient to keep the minerals dissolved. Maybe this could be achieved with something like a Yugang reactor that could also incorporate some cool hardware features into the setup.

 

[Randy Holmes-Farley]

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.