120 gallon tank and water changes

Hello Everybody ,

I've been keeping fish for about 20 years now . I have 2 30 gallon long tanks , 2 20 gallon high tanks , and 4 10 gallon .

I do a 15-25% water change on all tanks once a week . I use the python system to vacuum all the tanks and then refill them with aged water I keep in four 5 gallon water jugs . I have never used a water conditioner and never had a problem with ammonia .

Now to my problem , For christmas I bought my son a 120 gallon tank , set it all up and about 1 week later thru in 4 sets of guppies to cycle the tank . In the following 2 weeks the tank was going great . It got alittle cloudy at first and I was measuring about 1-2ppm of ammonia . The tank then cleared up and I was measuring 0 ammonia but about 20 ppm nitrates , so I figure its time for its first water change .

Now a 25% water change means I need to fill the tank with atleast 30 gallons of water , way past the capacity of my aged water reserves so I go to my LFS and they recommend I use my python to refill the tank with tap water and then use STRESS COAT to condition the water . Sounds easy enough but guess what , two days after I perform the water change some of the guppies are just laying on the bottom with thier fins clamped close to thier bodies . I test for ammonia and the water in the test tube turns dark blue (yellow meaning 0 ammonia dark green meaning high) . Whats going on ????????? Since when does a water change make thins worst ? How do you people do water changes on your big tanks???

Sounds like NITRITE poisoning. The tank has completely cycled - are you sure?

It sounds, from your description, to me, as though you may have interrupted the cycle after the ammonia spike.

I have a 54 gal corner tank and replace 10-20% of the water straight from the tap (bi-weekly) and don't have any problems. 25% change is a little larger than normal. Maybe buy a couple more of your 5 gallon jugs and stick to 10% water changes.

Also, did you use filter media from your previous tanks to help the cycle along?

I use ~25g plastic barrels from a local supply store. They look like oil drums, but are smalller, and have a closed top. There are two 3' openings on the top that are threaded, and you can fit 3/4' plumbing fittings to it. They fit under my stand to age, and also equalize at the same temperature. I have recently fit a 360gph pump to them so that I can sit back with my coffee while my tank drains.

If you are interested in photos, e-mail me and I'll make some.

After reading what I wrote, I should have indicated that my room is set to the temperature of my water - 70 degrees F. I don't use heaters since I keep 'coldwater' fish. Obviously if you have tropicals, you'd still have to get the temperature within reason before refilling with the aged water...

Four pair of guppies in a 120 gal. tank for two weeks wouldn't even have hardly started the cycle, let alone being able to show up on a test kit. In a 120 gal. tank, if your going to cycle it using fish, you will/should use more like 30 fish that size, about one third the total bio-load. Even with a bio-load that size, a cycle (0 ammonia, 0 nitrites) would take at least 4 to 6 weeks to get through the first stage. Then, as you add small groups of fish to finish stocking the tank, you will have mini spikes. Mini spikes are shorter (time) spikes (ammonia/nitrite) than the first cycle, but can be quite high, depending on the bio-load added. A *fully* cycled tank that size, cycling with fish, can take 2 or 3 months (or more) to cycle. That's a *lot* of water changes due to high ammonia and nitrites. If I were you, I would remove the guppies and do a fishless cycle. (seed the filter with a little media from 2 or 3 of your established filters and add 5 drops of pure ammonia per gal. (5ppm) to the 120 gal. tank and in 2 weeks or so, the tank will be _fully_ cycled, ready for a _full_ bio-load..... To answer your question 'whats going on'; I would guess your tap water has chloramine in it instead of chlorine. Some times the water plant adds a higher % of dechlorinator, thus a higher % of ammonia. Most water plants has changed over to chloramine because it last much longer in the water. In chloramine, their are 2 chloride ions bound to each ammonia molecule, so you have to double the amount of declorinator. Some declorinators that work with chlorine, don't work on chloramine. I haven't used Stress Coat, but the name implys slime coat protection(?) Sodium Thiosulfate will neutralize both chlorine and chloramine, provides slim coat protection, stabilizes pH, helps to neutralize ammonia and can be bought from a wine-making supplyer, a lot cheaper than what you get at a pet supply store. It's also used for developing B & W photos and can be found cheap at camera shops....... Frank

I use 45 gallon rubbermaid trashcans that I got at home depot for preparing my water.