5 Gallon Tank New tank with existing media cloudy for several days


Heyo all! Long time lurker first time poster with a question on how to proceed with a new tank. I had a tough call placing this into the cycling forum or here, but I think this is most accurate since I’m using preexisting media and my question relates mostly to water cloudiness.

I am a week into the process of setting up a small (4.1g) aquarium for my desk. Things seemed to be going pretty steady until I kicked around some substrate planting the last round of greenery a few days in – almost immediately the aquarium clouded whiteish and has been since. I think it’s a bacteria bloom from what I’ve read and believe generally I can expect them (day 3 or 4 so far) so I havent been too concerned about that on its own.. but the cycle is making me a bit worried.

The aquarium is co2 injected and pretty heavily planted using controlsoil (first time using the latter); the ammonia produced by that was super intense at the beginning (>4ppm). I seeded the tank using media from my larger tank (some bio Os and filter material from a heavily planted 29g which has been up for about 18 months 0a, 0ni, 10na) so I assume that the cycling process is complete or mostly complete because I had one small spike of nitrites which appeared and disappeared within a day at the very beginning. Currently no aquatic life is in the tank since ammonia was so high and have been waiting for it to drop to acceptable levels before moving the residents into their home from quarantine.

However, as you can see in the graph I attached of my readings, it’s taking quite awhile for the ammonia to drop… probably 1ppm naturally over the course the week. And on top of that I watched Nitrates drop down to 0?! I assumed it‘d hold steady at the least given the plants and nitrogen conversion so the drop is a tad concerning in combination with the clouded water that popped up and near steady ammonia reading. I did a 40% water change yesterday since it seemed like the nitrite spike happened and while modestly clearer, it’s still pretty foggy in there.

Anyway, I guess my ultimate question is should I wait it out as-is? My intuition says things are still early and just might be moving slowly. But should I also consider something like reducing light or plan on a more/less frequent water change schedule? Really, my ultimate fear is that I managed to mingle out my media somehow and stall the cycling process. :(

Thanks for any help and advice. Its a bit confusing to me since I am starting with existing media and the process worked out a bit differently in my other smaller tank, but also don’t have too much of an oh-no urge since I can always pull more media, it’s early, and no one is in there, yet.

Aquarium deets:

Are you doing a fish in cycle, fishless cycle or was your tank cycled and you had a sudden ammonia or nitrite spike?: fishless, using existing media & aqua soil.

What is the water volume of the tank?: 4.1g
What type of water are you using in your tank? (tap, well, RO/DI, other): tap
When did you start cycling the tank?: 9/19
What type of filtration are you running on this tank? (sponge, HOB, canister, other): Canister (Fluval 107)
If canister or HOB list all the media you are running in it. (manufactured cartridges, sponge, etc.): 2 large debris filter pads, 1 small debris filter pad, 1 polish pad, bio max cylinder thingies, <- all Fluval or API product; and purigen (to help with initial tannins from driftwood and while I don’t always run, like to pop it in my tanks every so often).
Do you have good water agitation/surface movement?: I think so. Have been working on getting it perfect with co2 exchange.
What is the water temperature?: 76°f (summer room temp) but will be heated in winter to around 78°.

If fish in cycling
What is the entire stocking of this tank? (Please list all fish and inverts):

How often do you feed them and how much?:
Are they showing signs of distress? (fish hiding, staying at the top, looking pale, torn fins, etc):
Do you have live plants in the tank?:
If so are they healthy and actively growing?:

Products used while cycling
If this is a fishless cycle what ammonia source are you using? (fish food, Dr Tim’s ammonia, other): Aqua soil was initial source, planning on adding fish when levels become acceptable to them since using existing media.
If adding liquid ammonia how often do you dose ammonia in your tank and in what quantity? (1ppm, 2ppm etc.): n/a
If using fish food as your ammonia source how much are you adding and how often?: n/a
Are you using a dechlorinater and if so, which one?: seachem prime
Are you using bottled bacteria and if so, which one?: n/a
Did you add seeded media from a previously cycled tank?: yup!
What other products/chemicals are you using? (list them all): half dose of thrive-s on initial tank setup

Testing and cycling process
What was your knowledge of the nitrogen cycle before beginning to cycle your tank? (none, beginner, intermediate (please explain), advanced): I think advanced? I understand the process and I have a 29g that I cycled fishless with no prob and have been running without issues for 18m but this is the first time I’ve done anything planted so small (besides a quarantine tank 5.5G which cycled instantly and without issue twice when setup with existing media but no plants, soil).
What do you use to test the water? (API liquid, test strips, other): API liquid
(see below for tap water stats)!
Have you done any water changes and if so, when?: 1, yesterday
How much water did you change?: 40%
Did you vacuum the substrate?: no
Did you clean your filter, filter media, decorations and/or glass?: no
If using disposable cartridges have you replaced one recently?: n/a

*Parameters - Very Important
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.
Tank water:
Ammonia: ~2.0
Nitrite: 0
Nitrate: 0
pH: 6.3-6.8 (co2 injected so fluctuates a bit through day and night)

Tap water:
Ammonia: 1.0
Nitrite: 0.25
Nitrate: 10
pH: >7.6


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Cycled media from old tank doesn't mean instant cycle on the new tank, but it can help the process along.
That ammonia is a bit high for a tank that size, I'd focus on cycling 2ppm ammonia max but you aren't going to hurt anything at 3-4ppm it just might take a bit longer. And I would hope to god that you aren't going to stock that tank with anything that will ever produce that much waste especially with those plants helping things along.
Your plants are also eating up the ammonia and that's also where your nitrate went.
The Co2 will actually help. The nitrifying bacteria obviously use ammonia and nitrite as an energy source but they utilize Co2 for growth....its science.
What about oxygen? You need some serious surface agitation or some bubbles happening to help the cycle.
Don't get impatient, don't worry about the cloudiness, it will pass.
Keep testing your water until all of your ammonia can convert in 24 hours.
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Haha, no worries about waste overload - it will be home to a single betta when ammonia balances out and a single snail once PH raises to a more acceptable level. I currently have enough surface agitation that there’s constant movement/turnover and no skum buildup but can and will amp it up to get additional exchange going on - great idea!

Thanks for the confidence! Totally fine waiting, but just a unique experience for a first time setup like this (like you said, 4ppm is p high for a wee tank and ammonia turnover has taken a bit) so always nice to have backup to the nerves :)
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I would just give it time for all the ammonia to be leached out of the substrate. I do have to think the substrate is at the bottom of the cloudy water since it happened after disturbing it while planting. For now I would hold off on water changes unless the ammonia goes above the 2ppm you are seeing right now. Even 2ppm is pretty high for a tank this size but the cycle should move forward.

The small spike in nitrites and then drop to zero is what I would expect to see if using seeded media. It is possible the number of plants in this tank are using all the nitrates being produced.

I have to ask. Do you really need the CO2 running in this tank at this point in the cycling process? The pH level is concerning. A tank struggles to cycle at that level. The 6.8 is alright but the low reading is too low. .

A question about the tank the media came from? The amount of bacteria on the media is going to depend on the bio-load in the tank the media came from not the length of time the tank has been running. If just one or two fish there will only be enough bacteria to handle their bio-load so there wouldn't be enough in the media to handle all the ammonia the substrate is producing. If the tank is heavily stocked there will be a lot more bacteria.
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It’s funny because if I had waited one more day I wouldn’t of had to post this! There’s only a small bit of fog left and all stats are pretty consistent except ammonia which has dropped to about 1.5ppm now.

The media came from a 29g light-to-moderately stocked tank with ~23 fish, (harlequin rasboraw, pencils, and a few cherry barbs… maybe 100-150 shrimp? side note: if you have any recommendations for adding to my community or mixing it up, let me know!) It has been up and running for about 18-20 months now but never experienced an ammonia load like this, at least not since the beginning. It sits so steady at a:0, ni:0, na:5ppm that I only test it once every month and a half or so during canister cleanings or if something odd sticks out. I did test it before all of this and during of course though :p!

The biggest reason I am running co2 from the beginning is that I have planted some finicky plants that need lovin from the start (baby drawf tears, some buces, and a few others I am new to). The more minor reasons are that it also helped me establish good pipe positioning for flow and agitation during set up and I figured that during nitrogen cycling establishing, I could experiment on balancing it in a good 35ppm average in such a lil tank before adding livestock so I don’t gas anyone. I’ll admit, I did not expect the ph to start off so low given how high my natural tap is (>7.6), but I think that future watch changes should bring it higher and more in line with my other tanks given it went up about .4-.5 on average with the one... that’s my hope anyway. I’ll keep an eye on it :)

Pretty much everything has taken root and seems to show growth, which is good news too, and I am sure helping keep nitrates (like both of you said) and ammonia in check.

I am sweating no more!
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thank you for letting us know the issue is solving itself. Sounds like it is just a matter of time for the cycle to finish up and the tank will be ready for its new occupant. BTW: As you probably already know, There should have been plenty of good bacteria on the media you moved from your cycled tank to give this tank a great jump start.

I shy away from stocking advice since there are just too many choices. :)
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