Calcium Bleedin' Sulphate

[Vale!]

Yes - one of my 'Desert Island' films. "We have seen your historical documents, Commander".

Anyway ... Day 2 of several:

It occurred to me that I might get better pictures in relative darkness, so I delayed today's ridiculousness until sundown.

It also occurred to me that we could get an idea of the turbidity of the water by looking at how well, or otherwise, the airstones can be seen at the bottom of the water column. So I've had a bash at taking a pic using torchlight



The glass test suggested definite improvement. It's still v. grotty but there isn't a layer of snow on the bottom after a similar period of rest as yesterday. Maybe I dipped in the 'wrong' place - I'll make sure to extract from elsewhere tomorrow




Moriarty is behind this. I know it.

[Vale!]

Never Give Up. Never Surrender.

In a bit of a tizz here because, subject to confirmatory tests, I may have made some sort of breakthrough. I felt that I needed to step back from it for a bit and later re-engage with some quantitative tests. So I'm just burbling at you to help that process! If what I've done seems valid I'll likely delete this post and replace it with a more detailed report.

Firstly I have a confession to make. Not knowing what I didn't know about getting calcium sulphate into solution, my initial attempt was to assemble the required amounts of all the salts and dump them in the tank that is to host this water (Sheba 4). It took some time for me to realise that the infernal and persistent cloudiness was not due to the gravel 'dusting' but rather undissolved calcium sulphate powder. I've had a filter-floss trap running so it's not quite as bad as it was, but I was still worried that the size of the powder particles remaining might be just the right size to get under Daphnias' carapaces and discombobulate them.

I filled one pint glass with bathwater, and another with bathwater 50/50 with cloudy tankwater. That was yesterday and, so far no casualties.



Later I'll repeat using 100% tankwater against the control.


Now then - what happened this morning? Well I went to sleep thinking about this and when I woke up I had an idea : what if I could temporarily alter the physical conditions of the mix in a way other than temperature (which didn't seem to do anything significant) or pH (which is on the rejection list at the moment)?

One thing I knew I could control was its ORP (Oxidation-Reduction Potential, or Redox). And my go-to tool for doing that is hydrogen peroxide. So I put a tick of powder (I didn't weigh it) into a glass of RO/DI water. Gave it a stir and took a pic ...



I added a glob of 6% peroxide (again unmeasured but probably about 5mls) and attacked it with a teaspoon. This pic was taken not ten minutes later ...



It's all dissolved, so far as I can tell. Before peroxide, the ORP was around +177mV ; and after peroxide it was around +277mV.

So I need to repeat with measured quantities - assuming I can find enough containers! I also need to confirm somehow that what I've ended up with is a solution of calcium sulphate and that the peroxide hasn't converted it into something else. Any ideas?

[Mito]

https://tutata.me/reactions/19697
Any help?

[Vale!]

Ha! Thank you, Mito (and hello again!).

I came across that not an hour ago! Sulphuric acid and calcium peroxide are definitely not on the menu!

I had prepared three glasses with identical amounts of water (400ml) and of calcium sulphate (0.05g) but varying amounts of peroxide : 1 drop ; 5 drops ; and 10 drops. The latter two performed well in terms of dissolving the powder, and pH fell proportionately(ish) with the number of drops of peroxide. Now I know why!

I've yet to take pics of the barrel and the dip-tube test (it's still settling) but will do later. It appears that there was some invisible algae on the walls of the barrel and it has decided to become unattached. I may still be able to assess the presence of sulphate snow, whether falling or settled, with a bit of luck. At any rate, I think the barrel may be emptied and refilled tomorrow, so I'll get the pressure-washer out while I'm at it!

Apparently the solubility of calcium sulphate is 0.24g per litre at 20C. I'm wondering if I can use that to my advantage somehow. Something to sleep on maybe.

[Vale!]

Day 3:

Airstones are more visible and would perhaps be more so if it weren't for the lumps and particles of dead algae, as mentioned above!




I left the dip tube samples in a glass overnight, just to make sure, but there's definitely no layer of undissolved snow on the bottom ...




My main task for today is to get some sweetcorn frozen but I'll try to make time to reset the barrel with a different mixing strategy.

[Vale!]

The other thing I forgot to mention was the Daphnia.

I had refilled the test glass with 100% tank water yesterday and added equal amounts of food to both. There has been one fatality in the test glass overnight, so not significant at the moment.

There's a bit of drama going on with the tank itself, where it appears that they're changing the guard at ammonia-munchers' palace : the cycle has gone into reverse as a consequence (I think) of the change in water quality. I put in a tick of pot bicarb yesterday but that didn't get it going again ; I'll look at the phosphate angle when I can. I'll possibly write this up at some point if anyone's interested but the key takeaway is that the water I gave the test Daphnia yesterday contained a smidge over 1mg/l ammonia. This may have had something to do with that death - although it was a big fat thing, so its time may have come in any case!

[plankton]

Don't you know how old each daphnia is?

[Vale!]

Well, it's rude to ask!

Stupidly busy day but I managed to empty the barrel, refill it with 25L of RO/DI (I thought it might make maths easier, if that were possible) and fumble about in my museum until I found enough stuff to rig up a recirculation circuit ...



I added 3 grams of calcium sulphate - which, in theory, might deign to dissolve itself in 25L at 20C. I didn't really want to add anything else but when I checked the pH I thought it was way too low (5.38) so I relented and added the proportionate amount of sodium bicarbonate. At the moment it's pH6.34 which is better but not great. I'll see what it says tomorrow.

No further Daphnia deaths.

[Vale!]

Good news! I don't have 25L of water on my 'fish room' floor - T-Rex Waterproof Tape FTW!

Inside the barrel it's : 313uS and pH6.79 . I will probably deconstruct the rig and inspect on Sunday.

In the meantime I have a special treat for y'all. Oh yes!

Yesterday morning I put 2L of RO/DI into a milk carton together with 0.48 grams of devil's powder - the amount that should dissolve in that volume at 20C.



I took it out and gave it a shake every so often. I figured it should be close to frozen in an hour or two. I carried on inspecting and shaking ... through the morning .. through the afternoon ... through the evening ... and through the first part of night. This morning it still wasn't frozen, so I've taken it out (pic above) and am letting it settle.

I'll be back presently to report on whether or not it's all dissolved as advertised!

[Vale!]

Some success at last! The rightmost glass contains the water from the bottom of the carton. Del Boy approves.



Yes - it's all dissolved. Right. I've poured the solution (yay!) back into the carton and added a further 0.48g - you can probably figure out what I'm thinking. I've managed to stuff it back into the freezer where space has now been stolen by a box full of sweetcorn and two boxes of Yorkshire Pies which arrived this morning.

I shall report back tomorrow.