Changing substrate a week into keeping new fish?

[mjg87]

So I set up a 20 gallon long tank over a month ago, did fishless cycle and was finally ready for fish last week. Fell in love with some Corys and took them home. I let my three-year-old daughter do some of the initial decorating and now I realize that they would probably do much better with sand instead of the top fin black and rainbow gravel that we have. I was just wondering if changing it all at once would be a shock to the fish or the cycle or if I should just change to sand incrementally? Considering Caribsea sunset gold or Seachem fluorite black sand

[mynameisnobody]

What lives in the tank? Worst case, you could do half one week and the other half the next week. My gut tells me you’re good and you can do the whole thing with no issues other than possibly cloudy water. 

[mjg87]

9 cories, moneywort, a sword, rock and driftwood with Anubias/java fern. Used co-op root tabs previously

[mynameisnobody]

That’s actually perfect. Be sure to keep all the beneficial bacteria alive on all the plants, rocks, and driftwood. I would just swap it out and I don’t see you having any issues. If you’re confident doing a swap, go for it. If you need any help with the process, just post here and you’ll get a full walkthrough. Good luck

[Mmiller2001]

Expect a mini cycle.

[D191]

I would be doing it more for looks than being all that concerned about corys on gravel but should be fine. Get some fritzyme 7 to dump in post substrate change , don’t feed fish for a couple days 

[mjg87]

I wish I could find Fritz zyme 7 locally. Would safestart plus suffice?

[mynameisnobody]

I’ve changed full sand substrate from a 75 twice and nothing more than a small bacterial bloom. Gone in a couple of days, however it was running for close to a year at the time. 

[D191]

On 8/17/2024 at 6:38 PM, mjg87 said:

I wish I could find Fritz zyme 7 locally. Would safestart plus suffice?

Never tried it but assume it would be decent. Maybe check to see if bottle has a batch or expiration date before buying 

[mjg87]

So I did it. Cleared out the gravel yesterday, ended up being about a 50% water change, put in the sand today. Stable parameters, but I added purigen to try to clear the water from everything only to realize the damn bag had a hole in it, so now there’s purigen balls scattered all over the new sand. Should I be concerned about the cories eating them? There’s no decor or plants in the tank for now, sitting in buckets of dechlorinated water and I can barely see enough to attempt a sand vac. Any suggestions are appreciated. 

[mynameisnobody]

I would definitely get all of that out, I’ve never heard of any fish eating purigen so I don’t know the effects but it can’t be good. 

Edited August 19 by mynameisnobody