I always use *Pure* Baking Soda ( no caking agents or anything else ) to buffer PH and add KH to my remineralized RO water. Equilibrium doesn't have everything in it - and there are other all in one options like "SaltyShrimp Shrimp Mineral GH/KH+" But I like to have them separate - just depends on how much patience and fun you want to have Also good to have an occasional Fertilizer if you see obvious signs of mineral deficiencies.
Its important to Buffer your RO water like this to avoid PH Spikes and wake up to everything dead except the plants. Please look online for proper doses for Pure Baking Soda - Ive been doing it so long I kind of eye ball it at this point XD

Not really , bad things happen sometime like when away on a weekend etc ..
Having no buffer is not optimal in any of those situations . I like to plan for the worst.

I love the salty shrimp gh/kh+ product.
My tap water is only 12TDS "RO like" (best water in canada)
I use salty shrimp product in my nano tanks , but use bss as baking soda and my own diy gh booster in my bigger tanks .
diy gh booster
This maintains the golden 3/1 mag/calcium ratio.
CaCl 6 grams
MgSo4 7 grams
1 gram of this mix raises gh of 10G water by 1dGH.

Those things don't happen in a healthy tank.

It would take weeks....even months........not a weekend.

Did this actually happen to you? Or something you read?

Just saying there are loads of successful planted tankers from around the world who run very little or no KH. If you want me to to point them out, I would be happy to. It's not that difficult. Just good regular maintenance. I have KH at about 1.0, and and have been transitioning to zero KH.

And I would stand by my statement. If you have problems like you described, you have bigger problems, and probably really need to change your tank maintenance. Just being honest.

Greggs you've seen my tanks I don't have problems other than growing plants faster than i can give them away..

Hey nice to see your tank.

It looks great!

But that brings up an earlier question.

Did you yourself experience pH crash? If so, can you describe it?

Or is it something you read about?

I am asking as I have never know anyone who actually had it happen. I've only seen people refer to web sites that have been saying that low KH is dangerous for decades.

My guess has always been that those who experience anything like a pH crash have underlying problems that bring it on. But just a guess. Would be curious to hear your experience if you had one.

Yes I have seen PH Crashes on other peoples tanks . Our local water supply has 0KH and only about 10 TDS coming out of the tap. In Vancouver BC area PH Crashes with new members and come up from time people on our club fb site Always due to another mitigating circumstance Like an unfound dead fish etc , ie new aquarists not being on top of things .

Using Inert substrates combined with our tap water means it needs to be remineralized just like RO.
I know lots of people do KH0 tanks not denying that.
Personally I prefer to be safe than sorry.

I use RO/DI for the same reason Blue Ridge Reef does, left over from when I used to keep reef tanks.

I've been remineralizing with GH Booster and using potassium bicarbonate to bump up to 1 dKH or so (6g to 30 gallons of water). I use aquasoil.

Now I'm wondering if I should cut out the potassium bicarbonate. I was worried about having too low of a pH (it was below 6), but I'm keeping tetras and corys so thinking I should be fine with a pH in the 5's.

I'm also concerned about the issues with using DI (mixed bed cartridges) and potential pH swings as filter starts to get exhausted. My system has goes sediment cartridges ->carbon block -> RO membrane -> first DI cart -> second DI cart -> final product.

Should I figure out how to reroute the flow of the RO and replace the DI carts with additional sediment and carbon blocks, or just remove the DI carts? Is it worth the effort or should I just continue with RO/DI?

That was my point.

You have not experienced it yourself.

Every single time someone mentions it, it is in someone else's tank. Someone they know only on the internet.

My guess is you don't personally know these tanks. You have only read about them. And if someone has dead fish in their tank they don't know about, they likely have little clue as to what they are doing.

I have still never known a person who reasonably knows what they are doing have a pH crash.

But we can agree to disagree. Just saying that IMO low KH probably had nothing to do with it, and a complete lack of knowledge/experience did.

Agreed, I have been saying the same for quite some time now, but people still feel the need to add baking soda in their tanks, they don't realize that baking soda is also adding Na in there which could be a bad thing and eventually will buildup over time. plus most soil now days are design to eat away the KH to maintain low PH anyway. plant and fish really don't care about the KH at least IME.

someone mentioned something about the Brighty K, its common sense and easy to clone it when you know the chemical, even rotala butterfly calculator can calculate it for you. not just Brighty K, but you can easily clone anything that's in the market, long as they reveal the chemical list on their bottles.

look how easy it is to clone Brighty K

To reach your target of 0.21ppm dKH you will need to add 35.4492 grams (equivalent to 2 tbsp + 0 tsp + 1/4 tsp + 1/8 tsp + 1/16 tsp ) of KHCO3 to your 500mL dosing container. Add 20mL of that mix to your 50gal aquarium to yield:

Element ppm/degree
K 2.9258
HCO3 4.5660
dKH 0.2100

Thank you for your observation.
When I look at ADA fertilizer Brighty K instruction sheet, it says, “Brighty K has an effect of enhancing the buffering capacity of water and prevents decline in pH of aquarium water. Cation: Brighty K is strongly alkaline.” This means very high KH.

Thus ADA is still afraid of pH crashes and is still recommending adding KH to the water column. Because I wanted to be sure I checked data of 24 published ADA show aquariums. Their KH was ranging from 0.6 to 2.8 and up to 4.0 dKH. With average of 1.8 dKH. None was even close to zero KH.

That's strange, cause it doesn't sound like there too worried about PH crashes due to no KH. According to you anyway:

Very well, you didn’t take the bait. What I posted was not dKH but dGH. Still, the matter of fact is that ADA wants us to dose KH even though their substrate does the pH buffering. Injection of CO2 creates carbonic acid which is relatively mild acid, we drink fully saturated CO2 enriched beverages, don’t we?

Carbonic acid from CO2 injection can theoretically push pH as low as 3.6 but usually about 4. But ADA substrate won’t allow it. It will stabilize it somewhere around 5.5 – 6.0 pH. This still should not be alarming, in contrary, this is natural and preferred by most plants and soft water fish.

I don’t want to scare any low pH sceptics but here we go:

2.0 pH lemon
2.8 pH grapes
2.8 pH plums
3.0 pH strawberries
3.1 pH blueberries
3.2 pH apple
3.2 pH cherries
3.2 pH pickles
3.3 pH apricot
3.4 pH mango
3.8 pH blackberries
4.3 pH beets
4.5 pH bananas

As you can see low pH is natural and nothing to worry about.