Substrate for planted guppy tank

[Kirsten]

So, I totally love my endlers and platies, but I think I'd like to get a separate guppy & possibly swordtail tank next. I have naturally soft, neutral water, about 50ppm GH and 20ppm KH out of the tap, which the plants make even softer. My platies and endlers are happy with the wondershell and handfuls of crushed coral I scatter over the regular gravel substrate, and they do raise the GH quite a bit, but the KH is almost always close to 0. Luckily the plants also seem to help the pH stay relatively stable.

So for the guppy tank, I want to be set up for success with the best substrate for a steady supply of KH buffering, while also making my plants happy and hopefully looking good, too. Since I don't need a super high pH, I was thinking of going with old fashion crushed coral, but I love the fine and soft sandy texture of aragonite. I also love the look of black diamond, which I think would set off a guppy's colors really well, but realize I'd have to just supplement with crushed coral in a filter bag to keep that color consistent (and might put some brown vermiculite underneath to help support the plants).

What would you recommend? Are the benefits of aragonite worth the extra cost? Are the benefits of a coral substrate negligible enough that I should just go for black diamond and supplement? Is there another substrate I'm overlooking that you'd recommend over all of these?

Edited February 10, 2021 by Kirsten

[MAC]

I really like the aragonite. I have it in almost every tank in some degree, the look of it is ok but the benefits on my very soft water is great. 

The big box Co. store usually has the 10lbs bags for just over $5, hard to beat that. 

[Kirsten]

1 hour ago, MAC said:

I really like the aragonite. I have it in almost every tank in some degree, the look of it is ok but the benefits on my very soft water is great. 

The big box Co. store usually has the 10lbs bags for just over $5, hard to beat that. 

That's good to know! Thanks! Does it raise your pH significantly? I'd like to keep mine in the 7.2-7.8 range. Do you mix it with regular sand?

[MAC]

My ph is about 7.2 in the tank I just measured that gets 2 water changes a week and about 7.8-8.0 (hard to tell) in the tank that gets a water change once a month or so. Both have a couple pounds of aragonite in it. 

I mix the aragonite in with whatever I have on hand for the tank. It's a slightly off white color when mixed with pure white sand or pool filter sand but I don't mind. 

[MAC]

Here it is with plays and peagravel and eco complete mixed. The tank is out of control at the moment. 

[Kirsten]

9 minutes ago, MAC said:

Here it is with plays and peagravel and eco complete mixed. The tank is out of control at the moment. 

LOL wow! Guppy Grass Jungle! I love it 😄

[MAC]

Just now, Kirsten said:

LOL wow! Guppy Grass Jungle! I love it 😄

Pogostemmon Stellatus-octopus actually. The stuff is insane. I trim it back and it's good for awhile and then suddenly it has huge growth spurts and fills the whole tank in a matter of weeks. I love it! 

[Kirsten]

14 minutes ago, MAC said:

Pogostemmon Stellatus-octopus actually. The stuff is insane. I trim it back and it's good for awhile and then suddenly it has huge growth spurts and fills the whole tank in a matter of weeks. I love it! 

Whoa! Nice! I'm taking notes.

[Maggie]

I use about 2 cups of aragonite, which I thought was the same as crushed coral, in my 20L. I haven't recently tested GH or KH but my pH is consistent at 7.4. This is for my dwarf emerald danios and neocaridina shrimp. 

For comparison, my 45 gallon does not have aragonite, and its pH is about 6.6 and soft. This is for my harlequin rasboras and caridina blue bolt shrimp. I do add wondershell for extra calcium.

Out of the tap my water is soft and neutral - pH 7 and low GH and KH. 

[Brandy]

Maybe I'm just lucky but my guppies are doing astoundingly well, and my water is significantly softer than yours. Mutts are doing fine in water that is like under 30-40ppm with just a random handful of coral added. In fact, my water sounds a lot like @Maggie's.

I recently got brave and ordered some guppies from Texas that were likely from Thailand originally--obviously harder water. I used wondershell and coral to bring it up to off-the-charts hard, and I am slowly (very slowly) water changing back to my normal parameters. I have had 2 drops of fry and everyone looks amazing. I will hold the coral for now, and wait on the water to stabilize without wondershell, then start removing tiny bits of coral each week--Hoping that in a year they will be fully adapted to NW Washington water.

Recently my teen bought some guppies locally and ignored my advice to test and match the bag water, and he dropped them into very soft water with no adjustment. They were sick inside of 3 days, and it has been touch and go since I took over--added wondershell immediately and started maracyn and ichX.

I think the trick is just no sudden moves. They very much will adapt, if you go slowly. So a long story to say I would go with whatever you like to look at, and transition them to your conditions over time.

[Patrick_G]

I also like the look of Black Diamond but have soft water. As I build out my new 75gal I’m considering adding filter bags of crushed coral under the aquascape and capping with the BDS. Any thoughts on this method? 

[Brandy]

25 minutes ago, Patrick_G said:

I also like the look of Black Diamond but have soft water. As I build out my new 75gal I’m considering adding filter bags of crushed coral under the aquascape and capping with the BDS. Any thoughts on this method? 

I think you will not get enough flow past the coral to do what you need it to. It will work in a very very long time maybe, but you may water change out the minerals faster than they are released. I would test this in an empty tank if I were you, because tearing up a scape in a 75 would make me cry.