Switching Substrate from Gravel to Sand

I currently have a 180 gallon tank that has been set up for 5-6 years. For filtration, I run a fluval fx6 and a fluval 406 filter. I am currently in the process of restocking my tank and I have about 20 juvenile South American fish.

I am looking to switch my substrate from large sized gravel to sand to give my geophagus a more natural environment. The problem is, I’m worried about crashing my nitrogen cycle if I replace everything at once.

My gravel is currently about 2 inches deep, and just this past week, I vacuumed all of the gravel for the first time in years. There does not appear to be any adverse effects from vacuuming all of the gravel after so long and I am wondering if y’all could give me some recommendations for how to properly swap my substrate without disturbing my nitrogen cycle?

Also, I have read that I should thoroughly rinse my sand in a bucket before adding it to my aquarium. Are there any tips y’all could give me for doing this with about 150 lbs of sand?

 

When I redid my tanks (on a much smaller scale: 10-gallons) I was told to remove the gravel in sections and add the thoroughly rinsed sand in sections. So do a bit every day and monitor your parameters as you do so because you don't know what you might stir up when removing the gravel. So, you could remove a section of gravel and replace it with the same amount of rinsed sand so you're not using all 150lbs of sand at once. Just bit by bit and do a water change after if you see your parameters change at all.

 

What I did was laid out my sand, Got some mesh media bags. Scooped up some gravel and filled it up, and plopped some bags around the tank on top of the sand to let some of the BB colonize on to it. And then as time progresses start slowly removing a bag like every week. I really didn't have to as my stocking was light but just did it anyways. As far as rinsing 150 lbs of sand....i don't envy you. There is a plastic bottle method you can try where you fill the bottle with sand, and while capped/covered....submerge the bottle upside down....let the sand slowly come out and as water enters the bottle....most of the debris and dust will be at the top of the bottle along with the water. Once all the sand is out...keeping the bottle upside down....cap it or cover it and then empty the contents of the bottle out. I'm sure someone will find the YouTube video and post it here.

 

When I redid my tanks (on a much smaller scale: 10-gallons) I was told to remove the gravel in sections and add the thoroughly rinsed sand in sections. So do a bit every day and monitor your parameters as you do so because you don't know what you might stir up when removing the gravel. So, you could remove a section of gravel and replace it with the same amount of rinsed sand so you're not using all 150lbs of sand at once. Just bit by bit and do a water change after if you see your parameters change at all.

I will probably do that then. Seems like removing in sections will disturb my biological bacteria the least. I may even do a section once a week just to be careful. How many sections do you think I should do this in? Thirds, quarters, or even more?

What I did was laid out my sand, Got some mesh media bags. Scooped up some gravel and filled it up, and plopped some bags around the tank on top of the sand to let some of the BB colonize on to it. And then as time progresses start slowly removing a bag like every week. I really didn't have to as my stocking was light but just did it anyways. As far as rinsing 150 lbs of sand....i don't envy you. There is a plastic bottle method you can try where you fill the bottle with sand, and while capped/covered....submerge the bottle upside down....let the sand slowly come out and as water enters the bottle....most of the debris and dust will be at the top of the bottle along with the water. Once all the sand is out...keeping the bottle upside down....cap it or cover it and then empty the contents of the bottle out. I'm sure someone will find the YouTube video and post it here.

I’ll try to find a video of that myself to see if I want to go that route. I understand what you’re saying though, it would probably keep a lot of the dust out of my tank. I will probably use that bag method as well just to be safe.

 

I will probably do that then. Seems like removing in sections will disturb my biological bacteria the least. I may even do a section once a week just to be careful. How many sections do you think I should do this in? Thirds, quarters, or even more?

Honestly, it's up to you. With my 10-gallon I did half at a time because it's small. Your 180-gallon is much larger so you could try doing 1/4 and see if anything comes up when you test. If nothing changes, do another 1/4 and repeat. If you see a spike in anything, do a water change and remove less than that next time.

 

How big is your gravel? In a 125 I had 3/8” gravel. I used a 3/4 hose and removed a 1/4 of the gravel a week while doing water changes. Replaced with new during the refil. I had cleaned the new much smaller gravel before. Kept the cycle alive with no problem.

 

Ypu should have enough nitrifing bacteria in your filter and decorations that it wont mater what you do to the substrate.
I have over the years, changed out all the substrate in a 29 gall tank, and in a 55 gallon tanks, for various reasons. the most recently, 10 months ago when i moved, i took out all the substrate from my 55 and washed it in chlorinated water, I didnt even put all of it back. I understand that you dont want to take risks with your fish. But I have removed the entire substrate 10 times in my tanks and i never once lost my cycle. I would just start scooping.

 

I changed from gravel to all sand in a 75 all at one go.
I just used a cup and scooped out the gravel.
Obviously used a Vickery to rinse sand, then used the cup to place the sand.

 

How big is your gravel? In a 125 I had 3/8” gravel. I used a 3/4 hose and removed a 1/4 of the gravel a week while doing water changes. Replaced with new during the refil. I had cleaned the new much smaller gravel before. Kept the cycle alive with no problem.

My gravel is probably 1/2 inch size. I believe I can easily purchase 1 inch tubing though, so that is probably what I will do to remove the substrate.

 

Removing it this way keeps the debris from floating all over the tank like when you scoop it out .

 

Removing it this way keeps the debris from floating all over the tank like when you scoop it out .

how did you get the gravel to go through the hose?

 

how did you get the gravel to go through the hose?

It’s the size of the hose. For the 3/8gravel I use a 3/4” hose. Yes sometimes it bunches up and you’ve got to clear it but as you go along you get the hang of it and the clogs are less . But this way the water stays clear .