Stocking a 30 gallon

[Thethorne]

Hi I’ve had tropical fish before but when I was younger. I’ve now got my own place and got a 30 gallon corner tank set up and cycled for about 6 months with 7 guppies and 6 corys all going great. So with the corys staying at the bottom and the guppies at the top I was thinking of getting a shoal of 12 cardinal tetras for the middle. Would this be ok or is that too heavily stocked. Also the tank has a few rocks and drift wood with a reasonably heavy planed back area. Thanks

 

[Byron]

What are the water parameters of your source water, namely the GH especially, and the pH?

 

[Thethorne]

My water hardness is 338ppm with ph between 6.5-7

 

[Byron]

My water hardness is 338ppm with ph between 6.5-7

That is a low (acidic) pH considering the very hard GH. Did you test the pH of the tap water yourself, or the tank water? Tap water needs to have any CO2 out-gassed or the reading can be lower than actual.

 

[utahfish]

Guppys are hard water fish corydora are sift water fish cardinal are really soft water fish and cardinals like a much warmer temp than corydora and guppy.
Your water is pretty hard and as such you should stick to live bearers, guppy, platy, mollies.

 

[Thethorne]

So I just done a fresh test on my tank water. Ph-7.2-7.6 kh-6 gh 330ppm

 

[Byron]

So I just done a fresh test on my tank water. Ph-7.2-7.6 kh-6 gh 330ppm

It is possible to have a high GH (indicating fairly hard water) and a lower pH, but generally they are closer. And the KH at just 6 doesn't fit either. What test are you using for the GH? And if it is tank water, is there something calcareous in the tank raising GH? Do you know the tap water GH on its own?

 

[Thethorne]

That is the tap water on its own from the thanes water website. It says we are in a ‘very hard’ water area. The kit I’m using is a jbl 6in1

 

[Essjay]

I have looked on Thames Water and used the postcode for the Spar shop in Berkeley Avenue. The hardness and pH are similar to those above but the KH is a lot higher. The low KH reported above could be due to inaccurate test strips

@Thethorne could I ask you to look at Thames Water again, and download the water quality report for your postcode, please. Just over half way down the first page you'll find Hardness (total) as CaCO3 and below that is Alkalinity as CaCO3 - alkalinity is what water companies call KH. Tell us the mean alkalinity please.

A few lines above hardness, you'll find "nitrate as NO3". It is worth making a note of that as well to check the accuracy of your test strips.

 

[Thethorne]

This is a screen shot of the water report. Thanks for all your help so far.

 

[Essjay]

From that table,

GH = 338 ppm, or 19 dH
KH = 271 ppm, or 15 dH (they call it alkalinity)
pH = 7.3
(and nitrate = 34 ppm)

The KH Thames Water give is very different from the test strip.

 

[Thethorne]

So just done another test strip here are the results.

 

[Byron]

Now we've sorted the parameters out, you are left with fairly hard water. Livebearers will all work, and there are some other species.

 

[Thethorne]

Could you give me some ideas of other species. I’m not overly keen on livebearers. Thanks

 

[Byron]

Could you give me some ideas of other species. I’m not overly keen on livebearers. Thanks

Not so easy. Some of the rainbowfishes require moderately hard water, but the species that do are the larger. What are the tank dimensions (I know it is 30 gallons)? Rift lake cichlids, but aside from shelldwellers, they tend to need more space. Members more experienced with these fish can advise better than I can.