Understanding KH & Carbonate Hardness - Do You Need It?

Carbonate hardness, also called kH, is one of the most commonly tested things in our aquariums, but what does it do and how much do we need?
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[@lukewang1997]

To expand a little bit on the technical answer, there are also some plants that will die with high kh. These are beyond "normal" like Eriocaulons and whatnot. At

[@dumbfishtanks]

Very interesting video but I'd like to bring up some counterpoints. I and many others on forums like UkApps, ScapeCrunch, Barreport, etc all have ran 0 kH tanks for many years now without any issues regarding fish health or plant health. The statement that plants prefer 6-8 dkH doesn't make much sense considering most aquasoils are designed to reduce kH to improve plant growth. I myself have experimented running tanks with 0 dkH, 2 dkH, and as high as 20 dkH and while the results tend to vary plant to plant, 99% of the plants did best in the 0 and 2 dkH setups. Most plants didn't seem to mind up until around 8-10 dkH, but they definitely did not prefer 6-8 as opposed to 0-2. While there are some plants (Val is one of them) that will use bicarbonates as a carbon source, the majority of the species out there do not. Part of the issue of running a higher kH level is it can raise the pH level high enough that certain plants will struggle more to uptake certain nutrients. Many species like guppies, neocaridina shrimp, rainbowfish seem to have this misconception that they need higher levels of kH, when it seems that it's really gH that's important. My neocaridina have not shown any changes in breeding whenever I stopped adding kH to my RODI water, same with my guppies, rice fish, and countless other species. I do make sure to do regular water changes and maintenance on said tanks and test my water to make sure it's stable. That being said I do add small amounts of crushed corral on my "nature" style tanks (no co2, dirt or clay based substrate) because I also add large amounts of leaf litter and I don't do nearly as many water changes on said tanks, keeping my kH usually around 1-2 dkH. Seems as though the leaf litter and corral balance each other out, even using 0 kH source water I still get a very stable 7.0-7.2 pH. I'm genuinely so interested in this topic that I'm considering investing in some pH monitoring equipment and running several tanks with inert substrates and different kH levels and seeing to what degree the stability is affected when running a very low kH.

[@Audiojunkabus]

I’ve just learned so much and finally understand things I’ve been missing for 37 years in the hobby. Thank you!

[@robvalero4453]

Just found your channel a few days ago and very glad I did. All of your videos I've watched so far have excellent knowledge and more of the experience talking I really enjoy hearing. Thank you for the details and a better way to understand the hobby sir.

[@bobcarter6483]

Bentley great video Mate 👍

[@seannunes2041]

This is a great discussion. Thank you for presenting. This is just what I was looking for.

[@shadeaquaticbreeder2914]

2:12 ooh science! I was that kid that asked why too much. I still do I'm just not a kid anymore lol. The science in it all is at least half the fun for me.

[@RoyalMetal9]

Very interesting. Especially the effect on fish. Thanks.

[@UncleSmileys.Aquariums]

Thanks for sharing actual good information.

[@jeremymoore450]

Bentley, What a great topic and explaining the KH process. I was hoping you would go into more detail about GH also. Maybe that could be another video. I do know that if a ph falls below 6 it significantly slows down the bacteria growth and the tank can crash. I usually try to keep my ph at 7 or close to 7 as I can.

[@ahmadsaidi8996]

Thank you very much for explanation, but Mr. Bentley I think pH not easy to drop it , you can see in ti tech planted tank you need to add ton of co2 injection to decrease pH 1degree and the fish not affected and as known most of aquascapers in hi tech using ro water (0 kh) and if they Remineralizing only for gh

[@BentleyPascoe]

@@ahmadsaidi8996 so in the case of your high-level aquascapes, the aqua soil itself does a type of buffering similar to what carbonate hardness does, but for keeping the water relatively soft and acidic. However, this only lasts for so long, which is why you see very high level aquascapes typically only existing for somewhere between 6 months and a year. Because the buffering capacity within the aqua soil only lasts so long. I personally prefer to use some level of KH to buffer water, but that's because my water has nothing in it. So I have a higher risk of pH crash if I don't buffer even while using aqua soil.

[@ahmadsaidi8996]

@@BentleyPascoe thank you very much

[@mauricematla8379]

I happen to live in a place on this bit of space debris where straight from the tap we get just about perfect water for your average livingroom planted aquarium. Also by law in this country i call home there is no crap in it in volumes that are problematic. KH 5 GH 8 PH 7,2 -7,5. Stable for the 4 decades i am playing this game by now. So i really never had to deal with these issue's. Except for when i played with the Paros family. But then it is "just" a matter of getting as low as you can on basicly all the stuff we tend to test for. Still i find it interresting in hearing about what other fishfreaks are dealing with.

[@davidspangler-dk8ug]

Again good stuff.

[@MorningDriftwood]

I have around 75ppm GH and 300+ppm KH (that's the highest my test kit can read so it may be higher). The only problem I get is I can't make a TRUE black water system without turning to distilled or RO water. It may be responsible that some plants just can't grow in my tanks but the one that I can grow are enough for me anyway.

[@-AndrewR]

👍🏻👍🏻 good info

[@josephgadway8950]

Can't thank you enough for covering this topic. We are moving. I'm worried about moving my fish from High ph, KH, to lower ph, 0KH. Scary. Will use baking soda to raise it some. Slow acclimate. Hope they make it fine. THank you!

[@BentleyPascoe]

@@josephgadway8950 so I live in an area where there is effectively 0 KH in my water and 0 GH in my water. For us in the Northwest it is super common to use crushed Coral to help buffer a little bit of carbon and hardness and general hardness. It's super easy. You just add a little bit test. Get yourself to a roughly stable area and then monitor it. Usually we just do this in a small media bag in the filter. Makes it easy peasy.

[@josephgadway8950]

@@BentleyPascoe OK Thank you. I will try is.

[@josephgadway8950]

@@BentleyPascoe Thank you very much!

[@jenniferrice5877]

New subscriber here. So glad I found you. 🐠

[@jeffkane4391]

So my tap water is liquid death at 28 tds ph 5.8 - 5.9 essentially 0 gh, 0 kh? All the lakes and rivers local to me test out at 30 tds 5.8 - 5.9 ph essentially 0 gh, 0 kh odd that they still support fish, snails, aquatic bugs, aquatic plants, and crayfish. I'm just checking in with some actual numbers and my supposed Midwest liquid rock in Northern Wisconsin that many KZbinrs insist I have... 😐😑😐 I was sharing my findings with StephenP over the summer if I remembered to get samples while I was out fishing. Water generalization does really irritate me. People willing to keep a fish in a glass box need to be willing to halfway know what is in their tap water. Shallow well, deep well, and city water is all different within the same county and even township even city water can very from block to block with old infrastructure. Talk about water has bothered me slightly this summer, but that is what I have seen and experienced.

[@BentleyPascoe]

@@jeffkane4391 wild, I'm guessing your water is all river fed like mine rather than well/aquifer fed.

[@jeffkane4391]

@BentleyPascoe rivers, seepage, and drainage lakes. My shallow well is above the bedrock, unlike my neighbors who do have hard water as well as iron issues

[@jeffkane4391]

@BentleyPascoe my well is snow melt and rain driven at the water table I utilize (25 feet deep)

[@toddbigeasy]

Good information. My tap is 7 ph and I keep mostly South American community or my rainbow tank. I do occasional check my tank ph always 7. I don’t test kh or gh . 😊

[@toddbigeasy]

I have plants and the nitrates are always under 20. I used to do 1/3 water change monthly but have increased to weekly cause why not 😊

[@helenprocter6919]

I find this very difficult to fully understand. Slowly but surely getting it as the months and KZbin videos go by.....thank you for your contribution.

[@AliCat876]

Thanks Bentley. Just added an fzone CO2 generator to my tank. Drop checker is green. Running it an hour before lights on to about 2 hours before lights off. My.kH has been around 70ppm and GH at about 200ppm. With pH at about 6.8. Testing later.

[@sschario60]

Falling KH, which allows pH to drop and acidify your water, will kill your beneficial bacteria. If this isn't the first time I've heard of this fatal effect on beneficial bacteria; it's the first time I paid enough attention to catch the important detail. Thanks again, Bentley 👍

[@dmm985]

Thanks for a great explanation, new to your channel and loving your vids. Can I ask????? If you are running CO2 across the day the PH will reduce fairly extensively. Is this normal/acceptable?

[@BentleyPascoe]

@@dmm985 you will see an impact on your pH, but it is kind of a false reading in a way. As long as you're not having a really drastic change, I wouldn't worry about it too much. This is why I personally go pretty low on my CO2 injection. It helps minimize that effect and also makes it so I don't have to maintain my plants like every week or so.

[@toothpicdinosaur3777]

I have forced spring water straight out of the Pitcher springs. Extremely soft water. I keep crushed coral and Epsom salts on hand. The water acidifies to the equivalent of battery acid in just a few months.

[@FernandoHernandez-cq9wn]

wish something like was out a few months ago, learned the hard way, after i lost a few fish, my ph would crash a day after water change, i would measure everything else, except ph, and took too long to notice

[@josephgadway8950]

If I add coral to my aquarium, would I still add baking soda when doing the water changes to bring up the kh Immediately? Should I also add the missing minerals ? The water at the new place has no minerals. Dang I bought Agrinite. That is all I could get. Thank you-

[@BentleyPascoe]

@@josephgadway8950 crush Coral will typically add both KH and GH. So what I would do is add crush Coral wait a week or so test and see where your numbers are at.

[@josephgadway8950]

@@BentleyPascoe Ok thank you. But when I do a weekly water change the water will be no kh. Will it shock my fish? Now I do a 80 percent weekly water change. 3 fantail goldfish in a 60g & 3 -50 gallon.

[@BentleyPascoe]

@@josephgadway8950 maybe try changing a little less water more frequently. Like doing 40% twice a week. In theory as long as you're filtration has a reasonable turnover rate even doing the 80% shouldn't actually take too long for it to get back up and mineralize through the crushed Coral.

[@josephgadway8950]

@@BentleyPascoe sounds good Thank you!!

[@snailsshrimpandmore5640]

Very informative video, thanks! I'm wondering how all of this relates back to aquasoils. My understanding is that they'll strip all of the KH out of the water (and I'm seeing this in my mini pond, which uses Fluval Stratum). How do you maintain a stable pH when using aquasoils? Or will the buffering capacity of the substrate exhaust itself before acidification becomes a concern? Thanks!

[@BentleyPascoe]

@@snailsshrimpandmore5640 not exactly correct. Aqua soil helps to buffer in a way that is similar to what carbonate hardness does, but specifically to help with stability in lower PH environments. However, that buffering capacity is limited. So if you're reliant upon aqua soil, you only will have so much time. This is why you typically see very high level. Aquascapes only exist for 6 months to a year

[@jdpartridge]

I would like to know what products we could use to adjust KH or GH separately if we are using RODI water. Do some products increase KH and others change the GH? I am using RODI because the water where I live is really good for growing algae instead of plants. I typically use the Seachem Equilibrium and then add some potassium and Seachem Flourish to the water separately as needed as a fertilizer, and then do water changes when the TDS is over 200. Seems to be working, but am I going about this wrong? Thank you for the video! Always learning something new form you.

[@darkstars-torpedoes-of-truth]

I know KH is extremely important for shrimp keeping, if you want them to survive. GH is too, but I think that I'm the only one who finds it nearly impossible to read in test kits.

[@danielm.6396]

Hey DT of Truth. Daniel here. I feel your pain. I'm into this technical stuff now for about 18months. Here's how I best now can get solid KH and GH test results. Get a standalone API KH and GH liquid drop test kit. Available all over everywhere. Second, this test requires 5 ml of tank water in the supplied glass test tube up to the little level line in the tube. Third, you will simply add one drop at a time of the test solution into the tube test water (and close top each time and shake) to look for a LITTLE change in water color. Now, IMPORTANT PART TO HELP YOU... Always open the top after adding another drop and shaking then look from the top of the tube down into the test water while holding the test vial somewhere near a brightish natural light like a sunny sliding glass door or a artificial light that is as close as bright white as possible. In other words, try to not use 3000K yellowish light if possible. That'll help. KH test.... test water changes from blue water tint to yellow. The number of drops needed to change the colors is recorded as the KH degrees. Similarily, GH test look for color to change from orange to green. Both test changes in color are subtle and you must look down into the test water by opening the top after shaking each additional drop in order to see the change in colors. Lots of drops, closing lid, shaking, open lid to look down for color shifts, then adding drop, etc etc. Lots of steps, but you will find stability in the repeated testing by going thru these steps. Hope this helps! Peace ✌️🐟🐠

[@darkstars-torpedoes-of-truth]

@@danielm.6396 Thanks for the detailed, well thought out reply. I use the API and the JBL kits for Kh and Gh testing, API with everything else. I have no problems with the Kh, but Gh, I just can't determine, I have to take it to the LFS now and then. These days my Gh reading is "if the shrimp are healthy, it must be ok". However, I had some test strips laying around that measures Gh at around 7, so I'm satisfied with that. Gh is just to subtle for me to determine in any type of light spectrum unfortunately.

[@bettalvr8800]

Great info! I apologize for asking newbie questions - but I'm confused. KH from my tap is 120ppm, but my aquarium water is showing 40ppm. That's according to test strips which I know aren't super accurate...but what could be lowering KH in my aquarium water??

[@BentleyPascoe]

@@bettalvr8800 a good question. Honestly I would try getting a liquid kit to verify first. Because it could be a false reading in the strips

[@frhaber]

I would love to find an economical means to cut my GH 31/KH20. RODI gets rather pricey for 9 tanks. lol

[@jenasteiner6611]

I have liquid rock from a limestone aquifer. Tested gh and kh with API kit. 31 drops for gh and I forget what kh was but it was sky high also. I have to mix with RO water and I’m not sure if I don’t mix right I’ll harm the fish bc the gh and kh will swing too much? I haven’t put fish in yet. PH very alkaline 8.0. And in my shrimp tank it’s 8.2. Shrimp seem ok but I’m not exactly happy with the high gh and kh Also phosphate is added

[@johnnybest6386]

Nice

[@pyleaquatics]

I have high KH and low GH. What would be a good way to raise GH?

[@dumbfishtanks]

Epsom salt for magnesium and gypsum for calcium

[@jenasteiner6611]

I have liquid rock from a limestone aquifer. Tested gh and kh with API kit. 31 drops for gh and I forget what kh was but it was sky high also. I have to mix with RO water and I’m not sure if I don’t mix right I’ll harm the fish bc the gh and kh will swing too much? I haven’t put fish in yet. PH very alkaline 8.0. And in my shrimp tank it’s 8.2. Shrimp seem ok but I’m not exactly happy with the high gh and kh Also phosphate is added and I’m debating adding a phosphate filter.

[@frhaber]

How much sodium does a water softener put in the water?

[@damiangrouse4564]

Folks, Think of an aquarium as a spaceship...you gotta bring everything with you.

[@stoneysscapes7544]

Fighting parameters takes a few things to get a balanced aquarium, and experience without a doubt is the 2nd but the hobby isn't going to ever have a decline of African Cichlid Members anytime soon 🤠

[@byz513]

Kh

[@bk2pla]

This explanation of the KH levels and acidification of the water from biological processes, really got my brain to finally “get it”. The “lightly consume” carbonates idea as part of how those processes works, clicked as to why that uses up KH and that causes the drop in pH (acidity) So thanks! Now I just have to use this info to figure out my low KH, high GH , pH neutral water, and what that means for how I maintain my tanks. This info will hopefully help me to attempt to stay awesome 🤩 👍

[@the186element9]

Liked # 176 / Algorithm

[@kens3dandaquatics]

First!

[@Anabolic_Ape]

I have high Gh and almost no Kh out of the tap.

[@Anabolic_Ape]

I use baking soda put it also increases Gh and Ph not only Kh. What do you recommend?