switching saltwater back to freshwater, help

bannershuffle · Aug 20, 2004

today i changed my aquarium from saltwater back to freshwater (it is a 125 gallon tank)

i drained ALL of the saltwater out, took out all the Crushed coral, all the large rocks/coral
and washed the entire inside with freshwater twice.
i also washed the filter very well and the media extremely well

there was nothing in the aquarium at ALL
then me and my gf washed every bit of crushed coral (approx 15 gallons worth) very very well until the water was crystal coming out of each batch, i even tasted a bunch of the batches with no problem

put the crushed coral back in, put two very well rinsed pieces of large coral in and put all 125 gallons back in

with the filter running and everything we put the test fish in and it lived all of 20 minutes before it just died almost instantly and rose nose first to the top at which it was going from dead to alive like an on off switch every 30 seconds
i hurrily put it in a container of pure freshwater w/ a huge airstone
but within 5 minutes it was dead
it never really gulped for air at all, so its probably not oxygen related

the specific gravity is at 1.00
which is freshwater... right?

is it the crushed coral?
a chemical still lurking from the saltwater

i put a bag of activated charcoal in the filter to hopefully absorb the problem
im gonna wait 36 hours before trying again

any opinions are appreciated

also, im gonna keep large fish, should i run my protein skimmer on the freshwater tank? or is it not useful

TKOS · Aug 20, 2004

Don't run a protein skimmer for a fresh water tank.

So the questions I will start with is. What is your water source? Did you add dechlorinator to the water? Could your water source have chloramines in it instead or regular chlorine?

How did you acclimate your new fish? I assume that with crushed coral in the tank the pH and hardness are nice and high, which may be very different than the fish store's. This could stress adn fisha dn kill it very quick if done wrong.

Have you read up on fishless cycling? There are stickies in the newbie forum that you should really read.

I would definately replace the filter media, though using the old filter is fine.

benjen · Aug 20, 2004

Be very careful using coral in a freshwater tank unless you are using a very small amount or you know you are keeping high pH tolerant fish (like most brackish fish). It dissolves in the pH of normal freshwater and raises the pH up to about 7.8 over time. Tetras and goldfish, for instance, might die if exposed to pH over 7.5, but can tolerate a far lower pH than any salt fish.

Otherwise, what TKOS said. Use a fishless cycle if possible.

OrionGirl · Aug 20, 2004

What was the test fish?

mogurnda · Aug 20, 2004

If I were to guess, I'd say the freshly cleaned crushed coral sent the pH and hardness way up. If the fish was transferred to the tank without giving it a chance to acclimate, it probably went into shock from the massive change in chemistry. Within reason, most FW fish can adapt to and thrive in a wide range of water conditions, but your tank is probably a bit extreme.

bannershuffle · Aug 21, 2004

new plan

it was a red belly pacu
I really thought it wouldn't have a problem

today i drained it again and took all the coral out
then i washed it all out again

i filled it with water again, so its just an aquarium with water and a filter,
nothing else

im gonna use a ditch minnow to test this time

thanks for the help

TKOS · Aug 21, 2004

What are you testing for? There is nothing a fish can tell you that a good test kit can't? And how are you acclimating these fish?

If you plan on having plants in this tank then add a substrate of some form of aquatic soil (really it is a clay substance like flourite) if you can afford to. Otherwise sand or gravel should be your choice for a bottom.

Adding a fish to an uncycled tank to see how long it will last seems rather silly to me. There is no benificial bacteria in the tank at this point so I can guess your readings are 0 ammonia, 0 nitrites and 0 nitrates and with a tank that size a single fish will not do much to change that very quickly.

You still say you filled it with water but what is added to the water and what is already in the water?

bannershuffle · Aug 22, 2004

i cant believe this,

i took EVERYTHING out the tank and filled it with water
and the **** fish died again,

there is nothing , no gravel, no filter, nothing

so problem is either water quality ( which i never ever had a problem with before)
or toxins still in the tank

i floated the bag in the tank for 25 minutes
same as last time

this time i lost an oscar i got on sale for 4.99
i was dead sure it was going to be fine this time

AW2EOD · Aug 22, 2004

I absoltutely agree with TKOS...

You keep adding a fish...it dies...you drain and fill the tank again...add another fish...it dies...the cycle goes on and on. It doesnt matter if you add a $.99 fish or a $50 fish...seems to me you wouldve realized by now that they're going to keep dying.

The whole point in keeping either a freshwater tank or a salt water tank is to provide those fish with the best possible environment to live in. Freshwater lakes, rivers, ponds, etc do not have fresh water from tap in them (it doesnt matter if you've added declorinator, etc. or not).

You need to set this tank up with filters, and either gravel or sand for a bed (dont use the crushed coral) and cycle it just like any "new" tank. If you're in a hurry, buy some Bio-Spira for freshwater and add that. That will basically cycle your tank in an hour or so. It's an easy fix, but not the best thing in the world.

Unless you do something to cycle this tank, your "test fish" are going to keep dying and not only are you wasting money, but you're killing fish for no reason.

bannershuffle · Aug 22, 2004

I cannot fathom why
a 1 inch fish cannot live in a 6 foot aquarium

i have had fish since i was in gradeschool and never had a problem like this


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switching saltwater back to freshwater, help

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