Question for danio fish owners about my water Kh in cycling planted tank

[mbwells]

If I’m reading this correctly (I’m partially color blind), then it looks like my water’s Gh is about 75 ppm, my water’s Kh is 0, and my pH is about 6.4. 
 

My aquarium is using Controsoil as the sole substrate, and it seems to be doing well with the plants. My plants are nearly finished melting and the Cryptocorynes and Rotala rotundifolia, and Java moss are all actually growing. I’ve been fertilizing with Easy Green and adding Easy Iron for my Cryptocoryne and Rotala rotundifolia plants every day for this first week, and I’ve just experienced my first bacterial bloom.
 

However, I’m getting closer to the point where I want to add fish to my aquarium. So far, my parameters have remained remarkably stable for the past 4 days, but the 0 Kh has me concerned that it might not stay that way with fish added in the mix.

 

Furthermore, I plan on keeping danios (like celestial pearls) and a pH closer to 6.8 would probably be ideal. Could anyone with experience keeping danios comment on any changes they’d personally like to see (if any) before I contemplate adding fish?

Thank you all so much for all of your help!! 

[Guppysnail]

Hi. I can’t help with adjusting water as I simply never do it. I do occasionally breed celestial pearls and keep 2 large colonies so if you ever find you have questions on them I can help. What are the readings for your source water?  6.4 is to low for CPD and zero kh is just scary. However while cycling with plants those two numbers can lower drastically. If your source water is acceptable parameters. I recommend do a series of water changes after your cycle is complete over the course of a week until you tank matches your source water and then aim to keep your tank close to your source water with continued regular water changes. 

[mbwells]

I really appreciate this information @Guppysnail !!  My tap water comes out at about 7.6 with about 75 GH and no KH.

 

I’m using Controsoil as my only substrate. It’s “supposed” to keep the pH around 6.8, but of course that’s with tested RO water. I’m new to the hobby and just wanted to see what would happen. Based off your information I’m wondering if it wouldn’t be wise to buy some crushed coral, throw it in, and see what happens after a week. 

[Guppysnail]

I keep my CPD at 7.6 ph 250 gh and 80-100 kh. That’s my tap water. 77.5 degrees and a decent medium decent flow.  Totally different than what I read on the internet but I’ve had them longer than I’ve been surfing the internet. They thrive are active front and center breed like crazy and fry thrive. I use either bare bottom tanks or less than 1 inch of inert gravel i. My plants of all types thrive as well. I avoid anything that alters water chemistry because the tanks are never stable for me and my fish and plants did not thrive. 

I would definitely add crushed coral to stabilize your tank

[mbwells]

@Guppysnailthat is amazing. Part of what got me into the whole Controsoil mess was going off the parameters of seriouslyfish. Just goes to show that just because something lives under certain conditions in nature doesn’t mean that those conditions are actually optimal or required. Appreciate the wisdom! I’ll go ahead and order a pound of crushed coral and wait a week. I’m in no hurry to add fish. 

[Guppysnail]

If you would like to change your soil I can walk you through it super easy. I change my tanks like folks change socks. Being new to the hobby is hard enough. Contending with substrate messing with things is beyond my ability and I’ve had fish most of my life. 

[mbwells]

I really appreciate your offer @GuppysnailI will try the crushed coral first and see what happens. I think removing all or part of the Controsoil would be a great step if the coral doesn’t boost my Kh. I’ll definitely take you up on your offer if I get to that point. Thank you again for all of your help. 

[Mmiller2001]

I believe that soil is a buffering soil and it's going to consume your carbonates for a good long while. Maybe for the next several months to 2 years. A long term battle with KH is not ideal. 

That said, and personally, I would keep the soil and try the CPDs. I keep all my tanks at 0KH. I wish I had your tap water, my life would be easier. 

Keeping GH and TDS stable is what counts. 6.8ph at 0dKH and 4dGH is really really nice.

FYI my Harlequin Rasbora are kept in 0dKH at a 4.85pH.

Edited January 7, 2022 by Mmiller2001

[mbwells]

@Mmiller2001 I'm sorry for just now responding, but I decided to take a few hours to do some research after seeing your post on Friday.  You are correct.  Controsoil is supposed to keep your water pH around 6.4 - 6.8 and deliberately removes alkalinity from water.  I did some fresh tests on the water parameters from my faucet, and learned that the water bottle I brought to the fish store had effected the results (despite washing the bottle 5 times!).  In glass bottles my water pH is about 6.8, my alkalinity about 40, and my Gh about 150. 

I looked through the research the company put out about Controsoil and everything you said checks out - the soil is *supposed* to remove carbonates and bicarbonates and use a humic acid based buffer instead to maintain a stable pH.  Moreover, my current results matches *perfectly* what the company claims should happen.  Initially, the soil should effectively remove all carbonate and bicarbonate salts, lower the water hardness, and the pH should fall to ~6.5.  Over time, this capacity should diminish, and my tank's water alkalinity and pH should gradually level off to the water's native parameters. 

Thank you so much for your thoughtful reply.  It led me down a very productive rabbit hole that helped me understand water chemistry better!!

 

Here's a link to the research:

https://ultumnaturesystems.com/substrate/