changing substrate

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Aquarium Advice Apprentice
Aug 19, 2023
so im changing my substrate sort of in a 75g tank, i have blue rock/black sand right now im putting in caribsea black stone that volcanic type because it is better for planted tanks which i want. im attempting to take out most if not all the blue stone it doesnt quite look good to me. and use black sand thats already in my tank as a bottom layer/then the new caribsea stone then a top layer of black sand.

im worried about ammonia spikes doing this. i never did this before so i am choosing to sections of my tank at a time. i did probably 1/3 or 1/4 of the tank so far and i do see more ammonia in my tank then usual. my tap water in FL always has a small bit of ammonia in it no matter what but after doing this i see more than usual. instead of being 0-0.5 it shows 1-2 ppm of ammonia. since this tank has been cycled for about a year now. is it safe to just put in seachem prime and run it like usual? i did put in some fluval ammonia remover packets in my canister filter to be on safe side but not sure if it will mess with my cycle a ton...should i keep them in or take them back out... i was planning to do another 1/3 of my tank tommorow or just doing the rest of it based on what the replys are. thanks as always
or should i just make it really easy for me and just put the caribsea stone over my substrate thats already in haha might save me alot of headache and time. the stone should cover my blue pebble rocks which i wanted to get rid of.
Plan to take a month to completely change the substrate. Do 25% one week, 25% the next week, etc. Plan to do additional water changes over this period to control ammonia levels. Leave the ammonia removing pouches in the filtration, but make sure they are last. They wont affect your cycle as long as the water is going through your biomedia before your chemical media.
ok, i put them first so i will change that, may i ask why that makes a difference though? oh i guess you just did explain why
appreciate such a fast reply also, do you run a fish store somewhere or something haha or you just been doing this awhile
Most of the time you want to go mechanical > biological > chemical. Mechanical removes any particles and detritus and helps keep your other media from clogging up. Biological then removes toxic nitrogen compounds, and lastly chemical media does whatever the chemical media is specifically there to do. There might be individual circumstances where a different order might be used, but mechanical > biological > chemical will almost always be a good way to go.

If your ammonia absorbing chemical media is before the biological media, there is a risk that the microbes in the biological media will be starved of food and die off. This happened to my manager who got advice from his dad to get some granular media to help clear up his water. I forget what brand/ product it was, but it looked like cat litter and must have been something like zeolite. I told him that these products only work for so long before they need replacing, i told him when it stopped working he might see a mini cycle because those microbes will have starved and died off to some degree. He is the kind of person who asks questions, but ignores answers when they arent what he wants to hear. About a month later his fish start dying, and when i tested his water for him, there was high levels of ammonia.

This is also why filter manufacturers include chemical media pouches with the filters or the cartridges have chemical media in them. They often recommend mechanical > chemical > biological and recommend changing the chemical media every 2 weeks or monthly. They understand how the nitrogen cycle works, and understand that setting them up with chemical before biological starves those microbes and prevents a tank from cycling. You are then going to keep going back to them to buy carbon or whatever. Setting up filtration properly is a far better practice than relying on chemical media. Chemical media has its uses, for example in your situation. But it shouldnt be run normally.

No i dont work in a fishstore. Just a hobbyist. Andy Sagar is our resident aquarium professional. He has certainly professionally bred fish, and i think he has worked in stores too.
Howdy fellow Floridian. :flowers: Where in the state are you?
As Aiken mentioned, I've worked not only in stores but also wholesale houses, owned my own fish import/ export businesses as well as commercial fish hatcheries. I don't believe there is any aspect of the tropical fish business that I haven't been involved with or consulted on over a 45+ year career. :whistle: ;)

As for the residual ammonia in your tap water, it's coming from the chloramine in your water HOWEVER, if your tank is cycled, your biological filter should be consuming that ammonia so your tank should be reading 0 ammonia. ( You need to break the chlorine/ ammonia bond that makes chloramine with PRIME or another conditioner that breaks the bond.)
As for changing over your substrate, as Aiken recommended, do a smaller section at a time but if there are fish in the tank, I would not do the next section until your ammonia level goes back to 0 after changing over the last section. That should be your OK to change more more than the calendar. (y)
very cool, im only like a year into this hobby but i enjoy it so much i might try to see about getting a part time job or something at a fish store once i leave my current job. i live in st petersburg FL.

sounds good on the substrate changing tip. i will certainly take my time.
very cool, im only like a year into this hobby but i enjoy it so much i might try to see about getting a part time job or something at a fish store once i leave my current job. i live in st petersburg FL.

sounds good on the substrate changing tip. i will certainly take my time.

Oh, so you are just down the road from me. LOL I'm about 80 miles East of you on St Rd 60. (y)
My buddy Jaime works at Consolidated Fish Farms over in Riverview. If you want some good fish, I'd try there. I've known him since he was a little kid ( early teens) and he really knows his fish. One heck a fish breeder as well. (y) (y) I used to breed Angels for his Dad at their fish store so I got to see Jaime in action. ;)
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