Approximating and Maintaining Water Chemistry of a Meromictic Lake

[Oldguy]

Stromatolite

On a lighter note about 2miles from my home there are fossilized Stromatolites in an exposure in a local abandoned quarry.
Good luck with your projects and keep us posted.

 

[hydrophyte]

On a lighter note about 2miles from my home there are fossilized Stromatolites in an exposure in a local abandoned quarry.
Good luck with your projects and keep us posted.

Would love to see pics if you ever visit the spot!

 

[hydrophyte]

I'm working on a spreadsheet for these dosage values. I'd like to get it to where I just have to use these four salts I have on hand—CaSO4, MgSO4, CaCo3, KHCO3—with other fertilizer added less precisely for N, P and traces.

Column C are the numbers in mg/L that @Heelllooo had calculated, with a couple of omissions.

With some more work this could be useful for recreating other unique water chemistries. But I need to make it more compact and logical for easier reading. There must be a couple of mistakes as well. And it does not take possible reactions into account...

 

[dw1305]

Hi all,

With some more work this could be useful for recreating other unique water chemistries.

That is what I use, an <"Excel spreadsheet with an embedded periodic table">. That is the <"basis of all aquarium nutrient calculators">.
I also have the <"solubility chart on one sheet">.

By linking to the elements in the periodic table, it stops you making inadvertent errors with RAM etc. and it allows you to create water with any particular chemistry (assuming you have access to a large range of salts). You can also link in wikipedia for salts <"Magnesium sulfate - Wikipedia">, because it has url's that don't move or change <"Clean URL - Wikipedia">.

Really flash nutrient calculators, like the <"IFC version">, just have a lot of added value (coding and formulae), hidden under the bonnet.

cheers Darrel

 

[hydrophyte]

Hi all,

That is what I use, an <"Excel spreadsheet with an embedded periodic table">. That is the <"basis of all aquarium nutrient calculators">.
I also have the <"solubility chart on one sheet">.

By linking to the elements in the periodic table, it stops you making inadvertent errors with RAM etc. and it allows you to create water with any particular chemistry (assuming you have access to a large range of salts). You can also link in wikipedia for salts <"Magnesium sulfate - Wikipedia">, because it has url's that don't move or change <"Clean URL - Wikipedia">.

Really flash nutrient calculators, like the <"IFC version">, just have a lot of added value (coding and formulae), hidden under the bonnet.

cheers Darrel

Yes I have a calculator like that on the first sheet of this file, although I had not linked the cells yet.

Did you configure your own calculator and do you have it somewhere? I know the answer is plain and obvious, but I'm having such a time organizing these rows and columns in a coherent way.

My approach is to first solve for the ions with the lowest concentrations (e.g. K) so that sulfates or carbonates in their salts (e.g. KHCO3) will be summed first and then work through the list to the more abundant ions.

Copy-pasting that handy solubility chart here...

 

[dw1305]

Hi all,

.... Did you configure your own calculator and do you have it somewhere? I know the answer is plain and obvious, but I'm having such a time organizing these rows and columns in a coherent way.

I do, pm me your email and I'll send it, but now I just use the IFC sheet.

Cheers Darrel

 

[hydrophyte]

I worked on the spreadsheet some more and I paste a jpeg below. Column C (in red) is filled mostly with the values that @Heelllooo suggested above, except that I omitted KNO3 and instead roughly doubled KHCO3 for the K content. MgCO3 is also omitted and I'm not worrying about silicates for now. NaCL is to be in the form of reef salt, of which it generally comprises about 90%.

3mg KNO3
4,8mg KHCO3
730mg MgSO4.7H20
1260mg CaSO4.1/2H2O
301mg CaCO3
29mg MgCO3
2,8mg SiO2

Here are the target concentrations that @X3NiTH suggested based on Green Lake data. I put most of these in Row 44 (in green) of the spreadsheet.

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

The bottom row (bold) sums the percentages multiplied by the mg/L dosages. Most values are pretty close, except that Ca is a good deal higher for the dosage (491.6mg/L) versus the target (420mg/L). I'm just confusing myself at this point the more I look at it. Can anybody see where I may have made errors, or is this pretty close? Also open to ideas for organizing this better.

 

[X3NiTH]

Don’t target for the Total Sulphate content as per the paper a lot of that is surface run off from anthropogenic activity (digging etc). If you use CaSO4 to target for both the Ca and the SO4 values it should be sufficient to reach the exact figure for Ca and have around 1000ppm SO4. Targeting the Carbonate value you can use MgCO3 to reach the Mg value first and then if addition of KHCO3 to the required level leaves you short on Carbonate rather than add more and go over the value for K or Mg you can swap out some of the CaSO4 for CaCO3 instead to get exact value for the Carbonates and stay in the same range for Ca but result with a lower total overall SO4 which is probably desirable in removing some of the anthropogenic load.

 

[hydrophyte]

Don’t target for the Total Sulphate content as per the paper a lot of that is surface run off from anthropogenic activity (digging etc). If you use CaSO4 to target for both the Ca and the SO4 values it should be sufficient to reach the exact figure for Ca and have around 1000ppm SO4. Targeting the Carbonate value you can use MgCO3 to reach the Mg value first and then if addition of KHCO3 to the required level leaves you short on Carbonate rather than add more and go over the value for K or Mg you can swap out some of the CaSO4 for CaCO3 instead to get exact value for the Carbonates and stay in the same range for Ca but result with a lower total overall SO4 which is probably desirable in removing some of the anthropogenic load.

OK I'll order some MgCO3 as well. While I wait for that to get here and while I clean up my spreadsheet I'm going to mix a small 4-liter batch of water tonight with a ballpark approximation. The samples came in the mail and I should get them out of the refrigerator and into water.

Here are some pics with CaCO3 crust on a glass beer bottle as well as sand sediment. Presumably the Cyanobacteria and other organisms implicated in the carbonate precipitation are present and alive, although I wasn't able to see much aside from the larger grains with this old Leitz microscope as the lenses are poor shape. Synechococcus and other coccoid Cyanobacteria best observed at 400X magnification or higher, but I was only able to manage 200X because the higher magnification objective lenses are broken.

 

[hydrophyte]

This is going to require some more problem-solving. There is a serious solubility issue with much of the salt mix remaining and/or reprecipitating as fine sediment. I ran a DC pump in the solution all night with no change. Here is the mix composition.

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

I suspect the gypsum as the problem, but mainly just because there was so much of it. I ordered some MgCO3 which should be here in a few days and for starters I'll try @X3NiTH recommendation for less sulfate.

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.

Do fine particles contribute to conductance? The TDS meter returned 697 ppm. Note the cloudy water even after the pail had been mixing all night.

For comparison the water sample from the lake was pretty close at 676 ppm

 

[X3NiTH]

At a minimum I would aerate the mixture to help with dissolution, if I wanted this to more rapidly solubilise I would bubble co2 through the mix to reduce the pH, it still could take a while to fully go into solution. I would prepare this mixture at least a week in advance of its use to fully let it go into solution and have clearer water without sediment.

Additionally or alternatively you can use a low molar acid to help reduce the pH more immediately and allow increased solubility in a shorter timeframe, HCl would increase the Chloride content overall and H2SO4 the Sulphate content. You need to use caution with acids so no high concentrates, 0.1 Molar is a sufficient enough concentration for pH adjustment.

 

[X3NiTH]

Can you post the brand of Reef Salt you are using and the batch number (some salts provide elemental analysis of content per batch) so we can get a better idea of extra minerals, obviously there’s not just NaCl in the salt you’re bringing along a 3:1 ratio of Mg:Ca and extra carbonates (usually 8dKH targeting 35ppt concentration) and also trace elements, these inclusions and any impurities in the other base salts in the mixture will be contributing in the higher TDS. Not anything I would be concerned about though as it’s really close.

 

[hydrophyte]

At a minimum I would aerate the mixture to help with dissolution, if I wanted this to more rapidly solubilise I would bubble co2 through the mix to reduce the pH, it still could take a while to fully go into solution. I would prepare this mixture at least a week in advance of its use to fully let it go into solution and have clearer water without sediment.

Additionally or alternatively you can use a low molar acid to help reduce the pH more immediately and allow increased solubility in a shorter timeframe, HCl would increase the Chloride content overall and H2SO4 the Sulphate content. You need to use caution with acids so no high concentrates, 0.1 Molar is a sufficient enough concentration for pH adjustment.

Can you post the brand of Reef Salt you are using and the batch number (some salts provide elemental analysis of content per batch) so we can get a better idea of extra minerals, obviously there’s not just NaCl in the salt you’re bringing along a 3:1 ratio of Mg:Ca and extra carbonates (usually 8dKH targeting 35ppt concentration) and also trace elements, these inclusions and any impurities in the other base salts in the mixture will be contributing in the higher TDS. Not anything I would be concerned about though as it’s really close.

Thanks very much! I'll let this run for a few days with the water pump and an air stone, then hook up CO2 if there is no change. If this composition is pretty close, then ions so close to or at saturation should advance the goal of biologically-mediated precipitation in the aquarium model ecosystem.

I don't see a Reef Crystals analysis published anywhere. I'd expect anything in addition to NaCl there to be pretty minor though as it was a small proportion (2.3%) of the whole mix.

 

[hydrophyte]

Revisiting the silica question and bookmarking this...just seven or ten dollars...

SpongExcel - Silica Solution

Overview Ionic silica solution for enhancing growth rates of sponges and gastropods. 1 drop per gallon of water increases ionic silica concentration by ~0.20 ppm. May be employed in silica-limited systems stocked with sponges to improve water quality by increasing the rate of natural latent...

www.bulkreefsupply.com

Silicate availability could be significant both for this setup idea and for the stromatolites tank...

https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1529-8817.1987.tb04444.x

In the months following set up for the stromatolites aquarium, benthic Diatoms were the predominant growth on the stones (pic below) as an amber-colored film, although more recently their coverage is much less and dark green Cyanobacteria are dominant...

Here's a microscope pic with benthic Diatoms from the Great Salt Lake field sample. I really need to get some better optics. This 200X magnification with damaged lenses is rather limiting, but you get the general idea anyway...

 

[hydrophyte]

I need to work on the salt blend some more, but I also want to get some of these live samples out of the refrigerator and into a tank. After a couple more days I saw no more change with water clarity, so last night I turned off the water pump to let the particles settle. Today I siphoned the clear water from the top and collected the bottom sediment to get a weight. All dried out it amounted to about 12% of the original salt blend...

I also got some values to compare the salt blend mix with the lake field sample and our home tapwater. A refractometer measured specific gravity, while I got the pH, GH and KH with cheap titration test kits. Water samples were room temperature, around 22C.

How do these numbers look?...

Here's this little 5G frag tank with eight liters of the blended water. This is just going to have to be good enough for now. It is pretty hard water. I'm also adding a few capfuls of prepared BG-11 nutrient medium as a very dilute nutrient source and with some light I hope this will get the Cyanobacteria and other microbes started...

 

[hydrophyte]

Blend #2:

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

This puts bicarbonate about 40 mg/L over the target value, but I think that's OK.

I portioned the CaSO4 separately this time and added it first to the mixing pail, where it dissolved readily. Some of the rest of the mix though stayed in suspension with sediment later falling to the bottom. I wonder about integrating a Yugang reactor CO2 injection to keep the heavy ion load in dissolution and with slow/intermittent water recirculation with the main tank...

View attachment 210741
View attachment 210742
View attachment 210743
View attachment 210744


degassed pH 7.93 | kH 8 | gH 14
Speece cone + Cerges | Plumbed into a T-fitting into the main pump | Injection Rate 116 cc/min | 0.8 pH drop in 2hrs
DIY Yugang reactor | Just an elbow in front of the main pump intake | Injection rate 100 cc/min | 0.86 pH drop in 2hrs

Yugang reactor is already a 16% improvement over my old set up, just need to tweak my injection rate to get a 1.2 pH drop.

 

[hydrophyte]

Duplicate post. Please ignore. See above.

 

[dw1305]

Hi all,

This puts bicarbonate about 40 mg/L over the target value, but I think that's OK. Some of the rest of the mix though stayed in suspension with sediment later falling to the bottom.

I wouldn't worry too much if some compounds come out of solution, they just form a buffer if the water chemistry changes.

I think all alkaline and / or salts rich water is likely to have that buffer. These are Neothauma shells in Lake Tanganyika <"Am i missing anything)?">, but the principle is the same in any endorheic basin like the <"Great Salt Lake"> or <"Lake Eyre">.

cheers Darrel

 

[hydrophyte]

Hi all,

I wouldn't worry too much if some compounds come out of solution, they just form a buffer if the water chemistry changes.

I think all alkaline and / or salts rich water is likely to have that buffer. These are Neothauma shells in Lake Tanganyika <"Am i missing anything)?">, but the principle is the same in any endorheic basin like the <"Great Salt Lake"> or <"Lake Eyre">.

cheers Darrel

I'm going to be very happy if I can get rock to grow. I already have several variations on setup ideas in mind.

 

[dw1305]

Hi all,

I'm going to be very happy if I can get rock to grow.

I'm expecting Mono Lake now <"Tufa">.

cheers Darrel