Questions about water parameters and fish choices for a new aquarium - low pH, KH, high GH

[PeteK]

Hi - I promised my 10 year old daughter a fish tank for her birthday with the original intent to set up a small 5 gallon to house a betta.  This would be our first aquarium in our home. I last kept an aquarium over 15 years ago.  During our planning stages, our 5 gallon blew up to a 20 long which is now setup with a pretty castle and a yellow submarine, as well as some live aquarium plants.  The suggested skull was vetoed.  While we wait for some plant growth to help season the tank, my daughter is eyeing friendly fish to live along with the betta.  Plans are to slowly add fish and some bottled bacteria once our plants appear to have taken hold for the next month.   In the meantime I ran some water tests using some coop test strips.  It turns out my water is running pH around 6.4, but is quite hard with a GH reading somewhere between 150 and 300ppm - its hard to tell which purple is which!  Oh, but my KH looks to be less than 40ppm. 

My first concern is that with the low buffering, my water is going to have a pH drop over time that will be hard to control. Does it make sense to add crushed coral or something to buffer the water now, or is it better to just let it ride and see how the water responds over time?

Also, fish choices - is it a strange combination to have hard but acidic water?  Is this going to limit what fish we can use in the tank?  Some original thoughts to join a betta would be some cories as well as some tetras or rasboras.  Are any of these going to be bothered by the water hardness?  What would be a good fish to start this fish in cycle with?

I appreciate any advice you have!

[xXInkedPhoenixX]

Hi there @PeteK welcome to the forum. I would suggest added crushed coral for sure, that will help with buffering and bring your pH up- it's a better and more consistent way to do this than with chemicals and won't be as wonky. 

The thing with Bettas....to properly keep them they require a temperature of at least 80 degrees, that kind of makes it uncomfortable for some species like Cory (though some of our Cory experts can weigh in maybe there's a species that can handle it well). I would also HIGHLY recommend Indian Almond leaves for your tank, this will help keep the Betta healthy. Despite popular big box store belief Betta fish are very hard fish to keep (just search on this forum, sick or dying Betta and you will see). Not trying to talk you out of getting one, I'm just telling you BE PREPARED. Personally I'd go with small tropical schooling fish- Ember Tetras for example are a great choice- you could get a school of 10 and still not have a big bio load and they will tolerate tank temps up to 84. Adults are usually less than half an inch and when happy are a very pretty bright orange. That's just one consideration. Some of the other species get bigger so you'd have a smaller school of 6 or so. ALWAYS do your research for required water parameters for all fish involved in the tank. Maybe others have ideas for a clean up crew or bottom feeders, most that I keep like temps around 78 or less (75 average) even snails. 

[Brian]

Maybe I missed it.   What are the parameters of the tap water?  
while the tank cycles the parameters can bounce around.  A seasoned tank can take months (8-9).  I would  not make a lot of changes.  I like to do things slowly.  Once you start changing things it could take several weeks or longer to see the results (good or bad) of the change.  So many people will change three or four things and often make it worse.   

[PeteK]

Thanks for the welcome and for both replies.  This is a very new tank. It has been set up for two days with only the plants added beyond the substrate, decor, and equipment. I do realize I am a very long way from having anything close to a seasoned tank.  I was thinking that getting some plant growth over the next month would get me to an environment where I could start introducing a couple fish while not having to stare at an empty tank fishless cycling.  The water parameters I quoted match exactly what I get from my tap.  I would think over time, the pH would drop further in the tank, hence my concerns about the KH reading and the possibility of a pH crash.   Plus I figure, if the current water parameters are concerning enough to think about making changes to the chemistry, that it would be better to do that before introducing fish. 

With regard to crushed coral - my concern would be it increasing my GH even further, limiting stocking options.  I have read some on the Indian Almond leaves as well, but wouldn't they counteract any adjustments crushed coral would make?  I've seen additives such as Seachem alkaline buffer that claims to raise pH and KH, without impacting GH.  But the instructions seem a bit confusing and I'm not sure if this is sustainable long term in the tank and if its the most cost effective choice.  I'm guessing I could always leave well enough alone and just closely monitor the tank over time to see how it responds. 

Thanks for the advice on bettas and other fish.  I had read the temperature range on bettas was a bit wider, from maybe 76F and up.  Indeed if I have to keep them at 80 or more, that is going to limit my options.  I was originally thinking to try and keep my tank at around 78F which would be a high end or beyond for some cories.   I'll definitely consider ember tetras as I imagine my daughter would enjoy them. 

 

[xXInkedPhoenixX]

I used to think that too @PeteK (temps 76-78 were good) but the more I've learned (and sadly lost) about Bettas is that in order to get the high humidity they require for breathing (they are labyrinth breathers)- to keep a Betta fish at OPTIMAL temperature it's actually 80-82. 

I have found GH not to matter too much unless you're keeping livebearers or discus (well and shrimp and snails). Most of our aquarium fish will do fine - especially if you get them from local sources that use the same water. I didn't personally see a crazy spike in GH (and I have hard water) after adding the coral. Yes you can use Alkaline Buffer (and I have- usually far less than they recommend does the trick by the way) but again you're chasing numbers there you don't really need to chase- especially now- focusing on the cycle at the moment is desirable. 

Personally I've been making IAL tea that I add to my water changes (boil a couple of leaves in a stockpot and divy it out into my water change bottles). It has not effected my tank water in a negative way. My tanks run in the 7.0-7.6 ph range (before and after adding the tea) with crushed coral in the substrates. It only has a very slight tint that you won't even really notice. It's antibacterial and great for your fish. It's even helped me to heal fish in the past. I was skeptical about it (though I drink a whole lot of tea myself so I should have known better) when  people would talk about it being a must in Betta tanks. IF I were to keep a Betta again (which I won't) that is definitely on the list. 

@Brian does have a point though. Tank isn't even cycled yet, while gh will probably stay mostly the same that ph is going to waiver a lot before it settles in especially without kh. I am willing to bet you'll see both of the last 2 numbers go up on their own once the tank is cycled. It might be best as you mentioned to leave it for some time until you know more. But I still recommend the crushed coral- far more stable way to get higher ph.