Keeping guppies in 0KH water

[Calamardo Tentaculos]

Hi all,

As I am making the transition to only using fully remineralised RO water, I would like to know whether it is good to keep guppies in 0-1 KH water. Is this ideal or with hard water fish like guppies, will having only 6-8 GH suffice or do we need to increase KH as well?

 

[hypnogogia]

What other fish will you be keeping?

 

[Bradders]

Well, if it helps, I have my water at 9 GH (160PPM) and 6 KH (107 PPM) with guppies, molly's and platy's, and all are doing just fine.

 

[Calamardo Tentaculos]

What other fish will you be keeping?

Cories I reckon.

 

[Calamardo Tentaculos]

Well, if it helps, I have my water at 9 GH (160PPM) and 6 KH (107 PPM) with guppies, molly's and platy's, and all are doing just fine.

Yeah, the thing is that you have a reasonably high KH which is I guess is bog standard for hard water.

I have read that KH is not important for planted tanks, and we merely need GH but I can't find anything about keeping guppies in such water (0 dKH, 8 dGH).

 

[Bradders]

I have read that KH is not important for planted tanks, and we merely need GH.

That is interesting, as (only recently!) I read something that implied the opposite:

We should quote GH and KH values separately, as the two values measures different things. When it is mentioned in the hobby that an aquatic plant requires "Softwater" it generally means that the plant requires low KH, not low GH. Aquatic plants are much more sensitive to KH values rather than GH values in the aquarium hobby.

We need someone on here to come and un-confuse this!

 

[Blinxy]

If you use buffer like aqua soil I think it should be ok, I had problems with caridina shrimp because my PH kept going too low so I had ammonium loose in the tank. One day my ph rose and killed all my shrimp bc ammonium converted to ammonia so I usually keep them on 1-2kh now to try prevent that

 

[Blinxy]

If you use buffer like aqua soil I think it should be ok, I had problems with caridina shrimp because my PH kept going too low so I had ammonium loose in the tank. One day my ph rose and killed all my shrimp bc ammonium converted to ammonia so I usually keep them on 1-2kh now to try prevent that

This was with pure ro water. A kh is good bc it prevents swings in PH.

 

[LMuhlen]

That is interesting, as (only recently!) I read something that implied the opposite:

We need someone on here to come and un-confuse this!

I'm guessing that he meant that increasing KH is not important for planted tanks. Not that the KH itself doesn't matter, but that we don't need to increase it. Indeed many say that most plants don't like KH, as your quote says.

 

[MichaelJ]

Hi all,

As I am making the transition to only using fully remineralised RO water, I would like to know whether it is good to keep guppies in 0-1 KH water. Is this ideal or with hard water fish like guppies, will having only 6-8 GH suffice or do we need to increase KH as well?

Your 6-8 dGH sounds reasonable. Given Guppies somewhat dislike acidic water it may be helpful for you to keep at least a few degrees of KH - say 3-4 in order to maintain a pH around neutral (pH 7) or perhaps slight above.

For a planted soft water tank where you also keep live stock that prefer acidic or at least slightly acidic water you generally do not need or want much or any dKH.

Cheers,
Michael

 

[hypnogogia]

Your 6-8 dGH sounds reasonable. Given Guppies somewhat dislike acidic water it may be helpful for you to keep at least a few degrees of KH - say 3-4 in order to maintain a pH around neutral (pH 7) or perhaps slight above.

That’s the one, and will also work for Corys.

 

[Calamardo Tentaculos]

@MichaelJ I know you've said this before, but what ingredient do I need to buffer KH again? Is it Potassium bicarbonate?

@hypnogogia I thought cories like soft acidic water?

 

[MichaelJ]

@MichaelJ I know you've said this before, but what ingredient do I need to buffer KH again? Is it Potassium bicarbonate?

With RO water as the starting point and having to raise the dKH 3 degrees Potassium bicarbonate would be my choice. Sodium Bicarbonate would add too much Sodium - but even with KHCO3 you will still get a lot of Potassium.

However, perhaps a better alternative would be to mix-in tap water to target the 3 dKH and use the Ca/Mg minerals to increase dGH up your dGH target... say your tap is ~15 dKH/dGH (not uncommon in the UK, but its more likely to be slightly higher dGH vs. dKH as you often have at least some magnesium in your tap) you would need to mix in about 20% tap to reach 3 dKH/3dGH and add an additional 4 dGH of the Ca/Mg remineralizer to reach 7 dGH.

Cheers,
Michael

 

[Calamardo Tentaculos]

Cheers for the advice @MichaelJ

However, I would like to avoid using tap water for the foreseeable future. We already have a contamination issue in our flats which is leading to a health scare so the safety of the water can't be relied on..

So potassium bicarbonate it is then unless you have any other advice?

 

[hypnogogia]

I thought cories like soft acidic water?

That would be their preference, but you’re going to have to compromise if you’re intent on guppies as well, hence neutral pH of 7 and a bit of KH as @MichaelJ suggests.

 

[Conort2]

@MichaelJ I know you've said this before, but what ingredient do I need to buffer KH again? Is it Potassium bicarbonate?

@hypnogogia I thought cories like soft acidic water?

What corydoras are you planning on keeping?

 

[MichaelJ]

So potassium bicarbonate it is then unless you have any other advice?

If mixing tap is off the table, potassium bicarbonate is the best advice I can give to raise the dKH... Unless your tank contains a lot of acidifying compounds, you're probably okay by targeting 2 dKH and provide enough buffering to secure a relatively stable pH around neutral 7 in your low tech tank (2 dKH from KHCO3 will add around 27 ppm of K). Adding some crushed corals works well as a backstop if the pH starts to crawls down. Back in the day when I was keeping Rift Valley cichlids (they like above pH 7 as well) I always felt it was a bit of a guessing game how much to add and what the net effect would be. I know Darrel/@dw1305 frequently recommend crushed coral, so I guess it can't be a bad idea.

Cheers,
Michael

 

[Calamardo Tentaculos]

What corydoras are you planning on keeping?

Pygmies, hastatus or habrosus

 

[John q]

(2 dKH from KHCO3 will add around 27 ppm of K).

Bloody hell Michael, suggesting somebody adds 27ppm of K! You heathen. 😆

BTW @Calamardo Tentaculos out of curiosity are you planning on injecting Co2 in this tank?

 

[Calamardo Tentaculos]

Bloody hell Michael, suggesting somebody adds 27ppm of K! You heathen. 😆

BTW @Calamardo Tentaculos out of curiosity are you planning on injecting Co2 in this tank?

Yes, I'll be putting co2 in all my tanks. Works like a treat