changing substrate with fish in tank?

[Hebdizzle]

would it be easy to change the substrate from a pea sized gravel to a sand substrate with the fish remaining in the tank? I want to do it on my 30 gallon . I would plan to do it in sections (to avoid killing most of the bacteria filtration) probably in thirds. I would use a bucket and small plastic shovel to take out the gravel by section, and replace it with the sand. I would have both my filters running on full capacity (of course) while I do this. My filters are a Fluval 204 and a Whisper 30.

Has anyone tried this?

thanks for the help
aaron

[Winnie]

I have added substrate (flourite) to two tanks with fish in them and that was freaky enough, and I have removed an under gravel filter with fish in the tank and that was pretty awful, although nobody died.
The problem with adding sand is the length of time it takes to settle - you won't even know where your fish are. You will panic and you will regret ever starting the project.
If you can put the fish in a big rubbermaid container with siphoned-off water in it, while you are adding the sand and for some of the time it takes to settle and re-decorate, I'd do that. It shouldn't be hard to catch them all with no decorations in the tank.
Those rubbermaid containers don't cost much and having one will come in handy.

[Aderynglas]

Hi,
I took out a gravel substrate and replaced with sand about 9 months ago, it was my 30 gallon tank, fluval 204 and no other filtration - the 204 is more than adequate for 30 galls :).

I took out half the water and kept it in buckets, the fish were then removed and placed in the buckets (neons, rosy and columbian tetras)

The plants were removed and put in a washing up bowl.
The gravel was then removed with a large fish net. The dirty water was removed and the washed sand was added, then fresh conditioned water and plants, the water from the buckets was added leaving the fish in the last bucket. the fish were then gently placed back and the water from their bucket was added to the tank. The fluval was only turned off while the water was too low for it to work and turned back on as soon as the water level was deep enough.

I didn't scrub the tank out (valuable bacteria) and the fluval 204 was well cycled.

I fed lightly for a few days after the change over and tested regularly for nitrItes and nitrAtes but there was no change in the water quality. The fish have remained in excellent health and my plants have definately shown great improvements. Root tabs are easily pushed into sand and the root systems are very healthy.:D

Hope this helps you make a decision :)

Regards
Polly

[OrionGirl]

I agree--you'll be happier if you remove the fish to change the substrate. If you are not running a UGF, then most of your bacteria colony will be concentrated in the filter media. Only the upper inch or so of gravel will have bacteria populations, and if you can scoop just this layer into a nylon baggie, you can save even this. Tie a knot in the bag, and sink the whole package in the tank for a week. The bacteria will migrate onto the new surface quite readily.

[Hebdizzle]

Thanks for the info guys... Come to think of it, I don't know why I even considered keeping the fish in. Aderynglas, did you keep the filter running during the time you were changing the substrates? I am worried about too much sand getting into the impellar.
Oriongirl, I used to have an UGF but I took that out about a month ago :).

I still haven't made a final decision, but thanks for the help, as I will take it into consideration!

Thanks,
Aaron

[anonapersona]

I took out some pebbles that were a top coat in my tank because they were affecting the water parameters and scared the hell out of my fish. Several came down with Ich, what a pain. Shoulda just taken the fish out to a bucket.

[125gJoe]

Originally posted by Hebdizzle
...... I used to have an UGF but I took that out about a month ago :).
... Excellent move! Applause! :)

[elmj]

is the underground filter a bad thing? i notice most of the lfs used it and actually wanted to buy one for my tank.

[SBA]

it seems the debate about UGFs never ends. Most people seem to agree that they do work if looked after properly (regular gravel vacuums + water changes). However they have a number of disadvantages.

They collect 'gunk' regardless of how well you clean the gravel (by their very nature they suck things into the substrate).

They don't work well with planted tanks (depending on what kind of plants etc).

They limit the choice of substrate to gravel (sand gets sucked into the filter).

They are a nightmare to remove if you want to at a later date.

They (IME) are a nightmare to clean if you have a fairly complicated setup (getting a gravel cleaner into those little gaps is not easy).

You can get anaerobic spots where things rest on the gravel (rocks etc).

Having said all that they provide a large surface area for the bacterial colony to establish itself and can work for years with out too much of a problem.

I have one in a 15 imperial gallon tank (came with the setup) which I really wish I hadn't used (didn't know any better at the time).

In my next tank I certainly won't be using one.

HTH

Edit:

a good link is this article by RTR:

http://www.aaquaria.com/aquasource/rtrrfug.shtml

[750t]

I posted this at an earlier date but I will post again. I changed the substrate in my 10 gal tank. What I did was remove the fish, I kept the hob filter full of water. Then I drained the tank and removed the gravel. What a mess. Then I took the tank outside and scrubbed it no cleaners of any kind . Added new substrate and filled tank. Declohred the water and put the fish back in. I monitored the water parameters very very closely. Everything was fine never any ammonia or nitrites. So the morle of this story in my opinon is the bacteria are in your filter and are capable of reproducing at a fast rate. I just want to add I just cycled a 45 gal with a sponge from a ac 300 on my 55. Never any any ammonia or nitrites. I just slowly increased the bio load. This is just my opinion only. Tim

[Aderynglas]

Hebdizzle
Sorry I didn't get back to you straight away, haven't been on the net lately :)

I kept the filter going until the last safe minute then switched off :eek: the filter was off for about 1 hour altogether as it was switched on as soon as possible. Water was gently poured over a newspaper to avoid stirring the sand too much :D

The sand will not get dragged in by your filter as long as the filter intake is not too close to the bottom, or you could fix a sponge over the filter intake if you are really worried :D :D

Good luck with it you won't regret it

Regards
Polly