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Cycling First Big Tank with Prawns

3K views 4 replies 3 participants last post by  lilnaugrim 
#1 ·
So, my mom surprised me with a 38 gallon special for my birthday, since my 10 gallon has been going so well as of late.

Anyway, this is the first time I've cycled such a big planted tank, and like a dummy, did a fish-in cycle for my 10 gallon.

I want to do this right this time, so I've planted a java fern, thrown in a coconut cave with some developing java moss, a couple of marimo balls, and I've got a large prawn inside to provide ammonia. My heater's going, but probably not heating well enough since it came with the tank set., (got a 200 watt heater on the way).

I've got an Aquaclear 50 filter going, along with an air stone, and eco-complete substrate.

Since adding the prawn three days ago, my values have been holding pretty steady.

Ammonia- 0.25-0.50 ppm
Nitrites- 0 ppm
Nitrates- 5.0-10 ppm

I added some gravel from my established 10 gallon to help jump start the cycle, along with a little water, and I'm limiting the big tank to about four hours of light a day, standard florescent bulbs that come with the hood.

So, here are my questions:

How long do I leave the prawn in? Do I just let it degrade, or wait a whole months?
Why am I already getting nitrate readings, but no nitrites at all?
Is the tank already cycled from the 1/4 cup of gravel I've already added? o_O

Can someone help me here? I really don't want to do anything wrong with this tank, given I've lost so many pretty fish in my 10 gallon.

Anything else I should know/change/do in order to set up my 38 gallon? Any help is appreciated!
 
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#2 ·
I'm actually not a fan of the rotting shrimp/prawns because it can promote Saprolengia which is a type of fungus. Instead, you can use Janitorial Strength 10% ammonia from a hardware store. It will take some getting used to in the dosing, but you can cycle quicker and immediately stock the tank right after. The Shrimp still only makes a certain amount of ammonia, so you won't be able to fully stock right away and will have to build up with time.

You likely have nitrates in your tap water, check that source to see if you do. You can have nitrates with no nitrites, doesn't mean your tank is cycled though until you see it go through the ammonia spike and then the nitrite spike and finally to nitrate spike.

No, your tank is not cycled yet, you'd have no ammonia and no nitrites if it were. :) Though, adding in that stuff helps out a lot.

Keep the water line lowered so that the filter can splash into the tank, doesn't have to be super low, just a couple inches down. The beneficial bacteria LOVE oxygen, so providing as much as you can will help them grow. Bumping up the temps around 82-86 will also help, they like the higher temperatures as well.

Do you know your pH by chance?

And do you know what you want to stock it with later on?
 
#3 · (Edited)
I haven't been testing for PH yet, because the guy at my LFS said that it wouldn't be necessary the first week or so, but I'll totally start checking again. As for ammonia, I guess I'm hoofing it to the hardware store. Any idea how much I should add per day to a 38 gallon tank?

As for what I want to stock, I'm going to go with cherry shrimp, mollies, a pleco, and some rummy nose tetras or zebra danios, depending on availability. I think my smaller snail is going to stay in the tank with my sparkling gouramis.
 
#4 ·
To give you an idea: I use 8 drops of Old Country Ammonia (10%) in my 10 gallon tank to bring up from 0 to 4 ppm ammonia. By next day it reads zero because the tank is cycled.
Use your Ammonia test drops to figure out how much and how often to dose. Don't overdose or you may crash the cycle.
 
#5 ·
It's good to always know your pH since if your pH is too low like mine is, you can't effectively keep a stable cycle and so you have to work with alternatives or bring your pH up to where it can support a cycle.

Make sure it's Janitorial Strength 10% Ammonia, I know ACE Hardware carries it. Make sure that it has no surfactant in it, that's bad stuff. Basically, it shouldn't bubble if you shake it, might be small bubbles but it shouldn't foam up like dish soap.

There are no real guidelines for dosing the ammonia unfortunately. It's good to have an ammonia test so you can see where the ammonia is at. You can use a dropper or a pipette to dose the ammonia, it will be smelly though, just to warn you. Here's a good quote from another site about dosing to help you:

"You should also run a little test to determine how much ammonia to add to your tank. Since medicine droppers come in all different sizes, it's hard to say that you need X drops per gallon to get to 5 or 6 PPM to start. I have 3 different droppers for adding fertilizers and for drawing tank water for testing and there is a big difference in the size drops they dispense. Take a small bucket, one of the buckets you used to fill your tank or wash you're sand. Fill it with water and then add 2 to 4 drops of ammonia per 5 gallon of water. Swirl it around to mix it and test to see what the ammonia reading is. Continue to do this until your reading is 5 to 6 ppm. Remember how many drops of ammonia you added and then, some simple maths will tell you how much to add to your tank to get the 5 to 6 ppm required to begin cycling. You can also use a test tube to add it. The amount required will depend on the concentration of the ammonia but 1ml (about 1/5th US teaspoonful) will usually raise 5 gallon to about 5ppm."

However, I don't agree with the 5-6 ppm of ammonia. The cycle will stall out if there is too much ammonia, generally right over 5 ppm of ammonia so you'll want to use about 4ppm of ammonia instead and keep it about there. If it drops, add more ammonia until it's back to 4ppm, if there is too much then do a water change. It's a bit of a process at first until you learn how your tank and your water reacts and you'll get the hang of it after the first week or so.

More from that site:

"Every time the ammonia drops back to zero, raise it back up to 3 to 4 ppm and continue to check nitrites. The nitrite reading will go off the chart. NOTE FOR API TEST KIT USERS: When you add the drops, if they immediately turn purple in the bottom of the tube, your nitrites are off the chart high. You do not need to shake the tube and wait 5 minutes. If you do, the color will turn green as the nitrites are so high that there isn't a color to measure them with. Once the ammonia is dropping from around 4 ppm back to zero in 12 hours or less you have sufficient bacteria to handle the ammonia your fish load produces. Continue to add ammonia daily as you must feed the bacteria that have formed or they will begin to die off.

The nitrite spike will generally take about twice as long to drop to zero as did the ammonia spike. The reason for this is two-fold. First, the nitrite processing bacteria just develop slower than those that process ammonia. Second, you are adding more nitrite daily (every time you add ammonia, it is transformed into nitrite raising the level a little more) as opposed to the ammonia, which you only add once at the start and then waited on it to drop to zero. During this time, you should occasionally test for nitrate too. The presence of nitrate means that nitrite is being processed, completing the nitrogen cycle. The nitrate level will also go off the chart but you will take care of that with a large water change later. It will seem like forever before the nitrite finally falls back to zero but eventually, almost overnight, it will drop and you can celebrate. You are almost there. Once the bacteria are able to process 4 or 5 ppm of ammonia back to zero ammonia and nitrite in about 10 to 12 hours. You are officially cycled."

So once that's all over, your tank might look a little crumby but that's okay. You'll be able to do a nice big 70-80% water change and clean to make it all nice again. The bacteria are stable in the filter and removing the water will not harm them. The only way you kill bacteria is by letting them dry out or exposing them to boiling or freezing temperatures. So as long as the filter still has some water in it, you're good to go and you can change as much water as you want. You'll need to do it since your nitrates will be off the charts as well by that point.

Sorry that was a big wall of text >.<

Since I don't know exactly what you do, just make sure that the Pleco is a Bristlenose, Rubberlip, or a Clown Pleco. Otherwise, the other ones get wwaaaayyy too big for your tank :) I will suggest to nix the cherry shrimp, they'll be eaten by your other fish; mollies get good at that since they get decently big. They also need a highly established and mature tank so that means your tank should be set up for a good 6 months at least before introducing them.

Zebra danios may stress out your mollies since they both inhabit the upper levels of the tank, Rummynose stay mostly in the middle and still school tightly so I'd go with them in order to not stress out all your fish ^_^ Danios also prefer cooler temperatures as well whereas Rummynose like warmer temps around 78-82 versus Danios down at 68-74
 
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