Changing Substrate In An Active Aquarium?

[clovis]

Hi all,
I turn once again to fishforums to help me out in this pickle I put myself into.
I have a 20 gallon long tank with 5 tetras, and 6 panda corydoras 6 red cherry shrimp, and 2 assassin snails.  I cycled the tank properly and all is going smoothly.  I had 4 corys, and taking the great advice here, I purchased 2 more to have more of a school.  I noticed that the two new corydoras had long barbs, while my older ones had none.  It became clear to me that the old cory had HAD barbs, but they have been completely worn down because my substrate was not fine enough, and has worn them down to nothing.
How do I go about fixing that?
Do i scoop out a bunch of substrate and replace it with smoother substrate (or is the word I am looking for sand)?
Can I do that with the fish in the tank or do i need to take every one out?
Does scooping out a bunch of stuff mess up the cycle/bacteria?
Do I just live with barbless corys? (that doesn't seem right to me)
Thanks for your help

 

[Akasha72]

hi, hopefully I can help here as I've done this a couple of times..
 
Firstly, you are correct, cories will wear down their barbels if you have a rough substrate and this makes it difficult for them to feed. We would never recommend keeping cories on gravel on this forum. Cories need to be kept on sand and not just to protect the their barbels, cories spend their time sifting through substrate in the search for food. This is their natural behaviour. I sit and watch my cories sifting the substrate daily and you can clearly see sand coming from their gills as they sift. This is natural too.
 
Okay, on to changing substrate. You can go about it two ways. You can catch all your stock and store them in a container - a bucket will be fine seen as you don't have a lot of fish. The problem for you is going to be catching the shrimps - I don't keep them but I understand they are not the easiest to catch. I think how ever you go about this you need to remove the shrimps at the very least as they are delicate.
Alternatively you can leave in your stock and work around them. To do this you will need to remove all decor and plants and concentrate on one side of the tank - removing the old substrate and replacing with new. Once you've done one side gently usher the fish to the new substrate side and work on the other side.
 
The best way to remove gravel I've found is with your net. Scoop up a net full and dump it in a bucket and just keep going until you've scooped it all out. You will end up with horrible cloudy water as you'll be surprised what's hiding in the gravel! This will clear eventually with the help of your filter and with partial water changes. It can't be helped and there's no way around it.
 
Personally, I would remove the fish. The process is stressful for them. As you'll have to strip the tank of everything anyway they should be easy to catch as there's nowhere for them to hide!
 
So as to the sand. You have a couple of options. You can buy proper aquarium sand, which can be expensive but it does give you a choice of colours - I wanted black sand and so I bought aquarium sand. The other option which is much much cheaper is children's play sand. It's non toxic and is perfectly safe for an aquarium - you'll be able to get a bag for a couple of pounds (I see your in France so that's be a couple of Euro's) Children's play sand gives a natural look so if that is what you are looking for this is the best option.
 
I can't go without pointing out (in case you don't know) that all sand, whether it be aquarium sand or play sand, will need to be washed and washed and washed until the water runs crystal clear. The best way I have found to do this is to add some to a bucket and put it under the tap with the tap on fairly high. To begin with the water will be brown and sludgy - just let the tap run. Once it starts to clear a bit get into the bucket with your hand and swirl the sand around as much as you can. You'll see debris coming to the top, pour that off and keep going. Once the water in the bucket is clear you can move on to the next bucket of sand! It's a long boring job but it will save you from looking at a brown aquarium for months. 
 
Hopefully I've given you enough information there and answers all you needed to know. If you have any more questions let us know, someone will be around to help if I am not
 
Happy sand washing, your cories will love you for it

oh yes, I forgot to say. Your cycle may be affected, it's difficult to say really. I would leave your filter alone (don't clean the media for a bit) and get a test kit if you havn't already and test the water daily (if not twice a day) if you see any signs of ammonia or nitrite then do a water change. You may get away with it, you may not, so just be mindful that you've taken away some beneficial bacteria with the gravel and keep a close watch on things. 
 
Good luck

 

[clovis]

Thank you for your wonderful advice, and taking the time to spell it all out!  Much appreciated

 

[Akasha72]

no problem. Glad to help. Hopefully I've covered everything you'll need to know

 

[frapadoodle]

Just a couple of notes, as Akasha did a bang up job.
Give your gravel a thorough vacuuming before changing. You will still have a mess of gunk, but it helps. Try a polishing pad or filter floss in your filter during the change to help catch the rest.
When adding the sand turn your filter off, but leave it wet. No matter how much you wash, there will still be some particles floating around, and they are murder on the filters impeller.
I agree about removing the fish, as it is less stressful on them than leaving them in the tank. I changed my first tank over from gravel to sand with only two fish in the tank, and it was an ordeal for me and them.
I second that the cycle may be affected, after all all that gunk is feeding the beneficial bacteria.
I also agree that there is nothing like watching Corys eyeballs deep in sand.

 

[Akasha72]

thanks for pointing out the bits I forgot Mr Doodles ... I'll second doing a good gravel vac before hand ... dig the syphon right in ... get right down to the glass if you can and wait for a few seconds ... give the syphon the hard work!
 
I also forgot about turning off the filter - yeah that's really important! Can't believe I forgot that!

 

[frapadoodle]

You have a lot on your plate kid. No need to fret the little stuff, it's a team effort.

 

[Akasha72]

 

[ProAquarist]

This is how I do it: Replacing the Substrate