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You are using an out of date browser. It may not display this or other websites correctly.You should upgrade or use an alternative browser. PH/KH/GH/Co2 problems

• Thread starter Thread starter dino21
• Start date Start date 15 Jun 2021

D

dino21

Member

Thread starter Joined 17 Mar 2020 Messages 374 Location Derbyshire Hi, Bit of a problem with our water and starting a new 60L tank, would appreciate some help please. Found that the tap water, which was always soft, is PH 7.5 out of the tap, but degassing down to PH 6.6 with a KH of barely 1dk (just 1drop on Api test kit) and a GH of barely 2. This moring the tanks pH , with just the substate in, is down to 6.4 by midday and have just tried a new different brand KH test kit with the same results. Our 3 year old tank with a standard aquarium gravel and sand did hold the PH up to 7.6 before the daily Co2, with a KH of 3 and GH of 5 though that has dropped a bit as the tap water must have been getting softer over the months. Know that the hardness need to be increased to keep the PH stable, but what is the best way to do that ? We will be using some well soaked wood in this tank. One other point we cannot quiet understand, if the waters PH is naturally down at 6.4, does that mean there is already 30ppm on C02 or Carbonic Acid in the water, so we don't need to inject CO2 ? Sort by date Sort by votes

dw1305

Expert

UKAPS Team Joined 7 Apr 2008 Messages 19,508 Location nr Bath Hi all,

dino21 said: Know that the hardness need to be increased to keep the PH stable, but what is the best way to do that ? We will be using some well soaked wood in this tank. Click to expand...

Just forget about "pH stability", it is important for Marine Aquarists but <"soft fresh water"> never <"has a stable pH">, and it isn't a <"problem for most fish">. If you keep Lake Tanganyika cichlids, or <"hard water snails">, you need high carbonate hardness, and a stable pH (they go together).

dino21 said: One other point we cannot quiet understand, if the waters PH is naturally down at 6.4, does that mean there is already 30ppm on C02 or Carbonic Acid in the water, so we don't need to inject CO2 ? Click to expand...

You can only use the pH ~ CO2 equilibrium values with a solution of known dKH. You will have somewhere between 0.6 and <"3 ppm CO2"> unless <"you add CO2">. cheers Darrel What is the “Duckweed Index” all about? Upvote 0 Downvote D

dino21

Member

Thread starter Joined 17 Mar 2020 Messages 374 Location Derbyshire

dw1305 said: Hi all, Just forget about "pH stability", it is important for Marine Aquarists but <"soft fresh water"> never <"has a stable pH">, and it isn't a <"problem for most fish">. If you keep Lake Tanganyika cichlids, or <"hard water snails">, you need high carbonate hardness, and a stable pH (they go together). You can only use the pH ~ CO2 equilibrium values with a solution of known dKH. You will have somewhere between 0.6 and <"3 ppm CO2"> unless <"you add CO2">. cheers Darrel Click to expand...

Hi, Thanks for those links to your previous posts, had not found them all before posting. Not sure why our water has become so soft, know we live near the moorlands but would not have expected it to have changed so much over a year or so and do not believe we actually get it first hand? Yes, we used to run a manine tank, hence getting hung up on hardness and ph, but todays few fish are just the usual communiuty fish. There is one more twist to the problem and one I know from reading some of your other posts you might again have some helpful comments, is that the new tank is being set up using Molar Clay and a silver sand topping as initially suggested by someone outside the forum. They also suggested mixing in some pure moss peat with the clay, but with that and the possible tannins from the driftwood( though well soaked) along with this now even softer water, do you think they could lower the PH too much ? Might it be better to remove the peat before we start planting the tank ? though believe the Molar Clay does not affect these parameters ? Upvote 0 Downvote

veerserif

Member

Joined 7 Jul 2020 Messages 75 Location Chicago, Illinois Hello, fellow aquarist with very soft tap water! So long as my KH and GH is stable, I now completely ignore the pH reading since it'll naturally fluctuate as plants photosynthesize and use more or less dissolved CO2. For reference, my water out of the tap reads ~50μS, >3 dGH + >1dKH (it's been a while since I've tested), and pH 9.0 since the water plant treats it with lime. After 24h it settles at about pH 7. My tanks stay around pH 7.4. I boost GH at water change with a commercial GH boost product, although I could mix my own with epsom salts and gypsum or calcium chloride. For KH, I keep a fistful of crushed coral in a mesh bag in my filter and also have some cuttlebone in the tank for my shrimp and snails to nibble. You could use crushed oyster shell, the kind sold as chicken feed, as a cheap alternative that will do the same thing. I don't actually have a target KH to hit, I just let it dissolve on its own and it will regulate itself in my experience. Obviously if you are trying to keep extremely soft water ignore everything I just said! Upvote 0 Downvote P

plantnoobdude

Member

Joined 17 Mar 2021 Messages 1,334 Location uk LOW ph/kh is no problem, mine is well below 6 and 2. i'd get the gh a bit higher in your tank, with a remineraliser, it could be plant uptake which is lowering your gh. I have a recent comment which explains how i make it if you want to know.

Anyone know where i can get TNC GH Boost?​

Uhm, take what ever is said above with a healthy dose of salt. Upvote 0 Downvote D

dino21

Member

Thread starter Joined 17 Mar 2020 Messages 374 Location Derbyshire Well now a little confused - as @dw1305 answer and his links - did not seem concerned about those low values and neither do you two, @veerserif and @plantnoobdude , yet you both up the GH and KH of your new water or via the filter. ? So if a low ph is nothing to worry about, in this context, why should we be increasing the hardness, not sure what the purpose is as from what DW says it does not affect the PH, if we understood correctly ? Upvote 0 Downvote

dw1305

Expert

UKAPS Team Joined 7 Apr 2008 Messages 19,508 Location nr Bath Hi all,

dino21 said: yet you both up the GH and KH of your new water or via the filter. ? So if a low ph is nothing to worry about, in this context, why should we be increasing the hardness, not sure what the purpose is as from what DW says it does not affect the PH, if we understood correctly ? Click to expand...

A lot of people run their tanks at very low carbonate hardness (dKH) values, have a look at @Roland 's <"Soft water tank">. There is also <"James' Planted Tank">. In water low in solutes you can <"just ignore pH">, it isn't a very useful measurement as you get <"towards pure H2O">. You need to add <"some dGH">, because both magnesium (Mg) and calcium (Ca) are <"essential nutrients for plant growth">. My guess would be that, if you don't keep black-water fish, then having a nominal amount of dKH is beneficial. If I was going to use water with no dKH I would definitely add <"some tannins to it">. cheers Darrel Last edited: 16 Jun 2021 What is the “Duckweed Index” all about? Upvote 0 Downvote P

plantnoobdude

Member

Joined 17 Mar 2021 Messages 1,334 Location uk @dino21 i keep kh low (0-2) , and gh around 10, exact number doesn't matter whether it be 20gh or 5gh if the Ca:Mg ratio is good. Uhm, take what ever is said above with a healthy dose of salt. Upvote 0 Downvote

veerserif

Member

Joined 7 Jul 2020 Messages 75 Location Chicago, Illinois Yep, as the others have said, I add calcium and magnesium for my plants, as well as for my shrimp and snails. Adding KH (and therefore stabilizing pH) is more of a side effect of throwing in cuttlebone and crushed coral for the inverts. Upvote 0 Downvote

ceg4048

Expert/Moderator

UKAPS Team Joined 11 Jul 2007 Messages 9,599 Location Almaty, Kazakhstan

dino21 said: Know that the hardness need to be increased to keep the PH stable, but what is the best way to do that ? We will be using some well soaked wood in this tank. Click to expand...

Hello, The necessity of pH stability is another of those old wives tales. Neither plants nor fish care about pH stability and in CO2 injected tanks the pH varies wildly over the course of the day. As mentioned by other posters, the need to increase GH is driven only by the nutritional requirements of plants or possible inverts for magnesium and calcium, however, the required quantity of these is miniscule and one only needs to add enough to raise the GH by 1 or 2 points. The need to raise the KH is driven only by the need to be able to reliably measure the pH. pH probes and reagent kits need a carbonate hardness of about 3-4 to read properly.

dino21 said: One other point we cannot quiet understand, if the waters PH is naturally down at 6.4, does that mean there is already 30ppm on C02 or Carbonic Acid in the water, so we don't need to inject CO2 ? Click to expand...

This is the worst of all wives tales and hobbyists really suffer the consequences when they subscribe to this. The pH/KH/CO2 chart was never developed for aquariums and is more of a laboratory quick reference cheat sheet. The chart makes the following assumptions: 1. That the acid is the in the water is 100% carbonic acid due to a tiny portion of the gas reacting with the water. 2. That the carbonate hardness (KH) of the water is caused 100% by dissolved carbonate/bicarbonate. These two conditions are easily met in a laboratory sample but are virtually NEVER met in real life for the following reasons: 1. Aquarium water and often, tap water always have some degree of dissolved organic and inorganic acid. We have no way of determining what percentage of the total amount of acid is carbonic acid, or how much of the pH is a result of the carbonic acid. 2. KH test kits CANNOT and DO NOT measure carbonate hardness. They are NOT carbonate hardness test kits, despite the fact they are labeled as such. They are ALKALINITY test kits. Alkalinity is defined as the ability of a water sample to resist change in pH. There are many water soluble substances, other than carbonate/bicarbonate which are capable of helping the water to resist a change in pH due to acid. Your "KH" test kit is incapable of distinguishing between carbonate/bicarbonate and these other substances, so it simply measures total alkalinity. The implication, therefore, is that both the pH value and the KH value that you use when reading the chart are completely corrupt and you will always read a higher CO2 content that is actually present if you use these measurements in the chart. Water that is sitting at equilibrium with atmosphere can only have, at most, approximately 8ppm of CO2. So you can see how far off you will be if you blindly use these two measurements in the chart. Cheers, Upvote 0 Downvote You must log in or register to reply here. Share: Facebook X Bluesky LinkedIn Reddit Pinterest Tumblr WhatsApp Email Share Link

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