First, thank you to all of the responses. For some reason my thread wasn't updating so I did some "cool" stuff that I will share after I comment on the responses.
How quickly are you adding the water to your tank? As adding it quickly can result in shock aswell. For me 20litres normally takes me about 2 hours. Iv done it faster before and my shrimp dart to the other side of the tank. For water temp reading. You can get yourself a TDs and temp pen. There like £6/$4 from eBay. Super cheap and really easy to use
Best of luck 👍
I suspect I am adding 1 gallon (4 ish litres of water) much quicker than that. The water change itself probably happens over 5 minutes at most? I do have my WC bucket sitting on top, a siphon into it (backwards set up for the vac) and into my tank so it is slow - but not that slow. The change would be more gradual, I suspect, if I slowed it down more --> what is everyone else's flow rate?
I read some of what was responded to you but not all, so if this was already said I apologise.
Can you please fill a bucket and leave in overnight with an air pump diffuser running inside to create surface agitation.
Take PH test immediately after filling and compare 24hrs later. I concur that your water parameters sound soft, so one would tend to think of a lower PH being present.
Give this a go and post your results. I would think you'd see some PH drop over that time sufficient enough to reduce shock to the fish and shrimp when completing a change.
That is a great idea - I had thought of "aged" water, but I thought this was just to remove chlorine ... I will try this and post my results.
PH swings may be something which changes as the water sets and gas is released, so one way to go might be to test tap after it has set for 24 hours and see if that gives a different answer. Sometimes it is practical and sometimes not but it may be worthwhile to try storing some water for changes as it can do both the offgassing and also let the water come to room temp. That's one of those things that may/may not work, depending on location?
For how much of any fert to use, I go to this calculator and then often adjust as I see how it fits for that tank as each tank is different:
Rotala Butterfly | Planted Aquarium Nutrient Dosing Calculator
This calc makes it a bit over 1/8 teaspoon (1/8 + 1/16??) so I might suggest starting at 1/8 a couple times a week as a way to "trial" it and watch for change.
Being from a farm background, where how to best treat the land is a constant question, I'm very much prone to testing, trying, and then adapting as I see what works. Plants are very forgiving and slow to actually die, while fish are less so.
Meanwhile, smaller and even slower water changes are one way to deal with sudden swings. Slow water changes are not my favorite thing, so smaller but more often fit me better. I keep sturdy (hard to kill!) fish and how to do things is always a matter of what fits each of us, so look at doing something like keeping a gallon jug full of water but open to air and maybe each day while waiting for morning coffee to brew? That gets you 20 % over a five day and things usually are not so critical that skipping a weekend is much problem, but look it over and maybe do more, less often if it feels right?
Good thing to watch how the fish/shrimp, etc. act and knowing what is normal is a really good thing as they are much more important clues than testing. If the test says it good and the fish say it's bad, trust the fish!
Perhaps I should store water for top ups as well -- your post coincides with the recommendation from @Jamo33
. Today, I think I'll put out two buckets ... one with an air stone and one without and test pH before and after for each (maybe just in the morning, then again at night). The only thing this should affect is pH, is that right?
... one thing is, then I will have to heat this water back to the temperature of my tank?
Great advice on trusting the fish.
NOW for the crazy thing. I dusted off the old chemistry textbook and tried to determine what amount of epsom salt would actually garner a 2 ppm change in a 5 gallon tank - Over 4 days, my tank used about 7ppm of Mg (since the initial water change), so 2 ppm seemed like a good call. So, I wasn't sure how it would affect GH etc so I dosed some into 1 litre of water to about 250ppm of GH ... my GH test just kept going ... the dosage worked ... blew my mind. After a bunch of chemistry (which I can post if anyone is interested), I came to the following:
0.3809100408 g of epsom salts will move my tank up by 2 ppm ... so I am like HOW do I measure that... I pulled out my kitchen scale and of course it can't measure it so I go to the tsp ... 1/16 of a tsp .3125 ish g was close enough for me.
Then I said hmm, I wonder if Rotala has epsom salt, they do, and I got EI dosing to be 2ppm Mg and the epsom salt to be 1/16 ... well lol -- I honed in on my chemistry skills and I can say that I confidently trust rotala butterfly for a calculator now.
Here were the problems:
1) pH in WC water (hope to reduce by letting water sit and/or adding an air stone the sitting water -- will test both)
2) Hardness (dose epsom salt ... could dose Calcium in a different ratio, if I notice some calcium deficiency ... it turns out that GH booster is just 3:1 or 4:1 calcium sulfate to magnesium sulfate ... I have no link just reading... might be worth calcium carbonate dissolved in to help with KH buffering ... becoming a mad scientist)
3) Temperature (bought two thermometers one for my tank, which I didn't have ... was relying on my heater being good ... I topped up my water today ... with an epsom salt dose ... and there were no adverse effects) FIXED
4) Flow rate -- thoughts?
Hope someone reads my novel above!
I will update the two bucket test with pH ... I'll also test ammonia because I suspect that the one with the air stone will reduce it more.