Tanks, Water, Bacteria, Algae, and the Nitrogen Cycle
Tanks and Aquascaping
Choosing the Right Tank
The main considerations when choosing a tank are the following: * What kind of watercreatures am I going to keep, and what size do they need? * Always go a lil oversized than what you think, and also consider that aquascape, substrate, and "room from the top" reduce tank size. A 14 gallon with as much stuff as mine is closer to a 10 gallon. * What kind of plants and filtration system am I going to use? * There are some filtration systems that go under the substrate in half of the tank, and that reduces your water capacity so you might need a larger or different sized tank to effectively house these systems. Additionally, if you are going for a flatter tank, different considerations need to be made. * What is my aesthetic going to be like? * There are tons of different options: traditional rectangles, cubes, long and flat, enclosed systems (EcoSphere), vivariums, paludariums, etc. * What is my space like? * Don't get eyes bigger than your stomach, or so the saying goes.
Tank Layout
Generally, any filter pumps should be in the same area as the heater so that the hot water is moved around and minimizes temperature gradients. Next, make sure whatever filter you get is the proper flow rate for what kind of watercreatures you are keeping, and when you set up your aquascaping, make sure to put some kind of 'underwater cover' like a branch or lots of foliage so that you don't have a 'deadzone' because of all of the flow coming out of your filter. If you are going to use a thermometer, keep it in the most opposite point of the filter and heater so that you can get an idea of the temperature gradient. You can assume that the spot right next to the heater is whatever the heater displays, but by putting a thermometer across the tank you can figure out the temperature differential, which also helps you figure out if you have enough flow.
Aquascaping with a Focus on Watercreature Health
The main idea of this section is to make sure you got enough stuff for the shrimp to much, the snails to slither, the fish to play with, etc. It is unwise to just create a 'monoculture' of a single plant because that does not provide the watercreatures the variety they crave. In the same vein, putting only wood alienates snails, which may have difficulty moving around on small pieces, while putting only thick rocks will provide less biofilm for the shrimp to much and the bacteria to grow on. If you are selecting a paludarium, make sure that the above ground part doesn't have plants or animals that will actively harm the underwater stuff and vice versa.
The Nitrogen Cycle, and Cycling Your Tank
What is the Nitrogen Cycle
The nitrogen cycle is the process by which animals, plants, bacteria/algae, and other organism convert oxygen, sugars, plant material, and poop into all of the other things. Take a look at this image:
You can forego frequent water changes (and sometimes all together) by heavily planting a tank. Plus, 90% of the fun is getting to see all of the life interact with the plants, looking for your little shrimp, etc. so why wouldn't you put plants and/or coral in a tank? It just makes sense!
Cycling A Tank
Cycling a tank is the process of generating bacteria (whether naturally, from a friend's tank, or via additives) in order to start the nitrogen cycle. For all intents and purposes, until the bacteria blooms, tap water is 'sterile', which means that in order for the VERY small amount of bacteria to grow and become beneficial, you either need a LONG time, or add bacteria in somehow (again, naturally from the water and time, from the soil or a local lake, from a friend's tank, or via additives). Once the bacteria starts, so does the nitrogen cycle. The decay of plants, the buildup of schmoo on the substrate (dirt/sand/rocks), biofilm and gunk on tank features, and other things will all have both bacteria, and stuff that breaks down into ammonia.
There is much debate about how long to cycle a tank before adding creatures. Cherry told me that a month is about right, but I have seen some fishtubers think it takes multiple months. Some people suggest adding snails and shrimp to help deal with the biofilm and provide their own bacteria in the form of poop and gunk on them from wherever they came from, but the facts are clear:
- Adding lots of plants helps speed up the process. The more plants the better. Plus plants are cool, so why not?!
- Adding snails can also help speed up the process and keep the tank nice at the same time.
- Adding shrimp is risky for the shrimp but can help speed up the process and clean up biofilm and algae really quickly.
- Adding snails and shrimp add other stuff too (some beneficial, like bacteria from other tanks, but also some bad like bladder snails and other pests that you may or may not tolerate)
- Water changes can help keep the process stable and prevent buildups of various 'badstuff' by removing nitrates, nitrites, ammonia, debris, and detritus (poop and other organic debris that cannot or has not yet been broken down)
I believe that a good marker is cycle for a week with plants from the beginning, add snails at the end of the first week. Add shrimp at the end of the second week to the middle of the third week, and then fish once the whole thing looks fairly cleanly, but not before the 4 week mark. If you have enough plants, the plants should also begin to really grow in at this point, so that also helps.
Water
Quality and Testing
Water in a tank has several components that can help determine the water quality.
pH - Acidity
pH is the acidity of the water. Most fish like a pH of 6.5 to 8.0. pH generally doesn't matter too much if your KH levels are good and you aren't trying to do fancy stuff like keep specific fish or breed some fish that like more basic or acidic water.
KH - Carbonate Hardness
KH is the amount of carbonates and bicarbonates in water, which is basically how resistant to pH change your water is. Higher KH means you get less pH swing. Freshwater aquariums should be between 4-8 dKH (or 70-140 ppm). Whether or not a watercreature is effected by low or high KH is specific to that animal, but generally, you want some reasonable levels.
GH - General Hardness
GH measures the amount of calcium and magnesium in the water, also known colloquially as the hardness of the water. These minerals are essential to the function of your creatures. helping in ways like as muscle, bone, and shell development, molting, and plant growth. Freshwater aquariums should have a GH between 4-8 dGH (or 70-140 ppm). Certain fish like harder water, while some only breed in softer water (3 dGH or 50 ppm). This isn't super super important like the rest of the values because watercreatures are pretty hardy against a lot of the minerals.
Low GH, on the other hand, can cause:
- Poor appetite
- Slow growth
- Lethargy
- Faded colors
- Trouble with moulting
- Thin, flaky, or pitted shells
- Plants with mineral deficiencies
GH measures magnesium AND calcium, so you could have plenty of one and not the other and it will still cause issues and test fine.
TDS - Total Dissolved Solids
The TDS of the water is the total concentration of dissolved stuff. TDS includes KH and HG values, as well as a small amount of organic matter and other solids that don't apply to either. The best TDS for each watercreature, like all other values on this list, is whatever is the closest to the natural habitat of the watercreature. Different watercreatures require different TDS values, with 400 - 500 PPM being good for most watercreatures. Too high of levels kill watercreatures and allow algae to bloom more effectively (which is sometimes-usually bad), and lower values cause watercreatures (particularly fish) to grow more slowly.
NH3 - Ammonia, NO2 - Nitrites, and NO3 - Nitrates
Ammonia is the most harmful thing for watercreatures, and is super deadly. It comes from poop, pee, and decay (please reference the Dung Eater from Eldin Ring, he probably smells like fish and death). While Ammonia is essential for the Nitrogen Cycle (and is what most bacteria feed on to create Nitrites), it should fluctuate between a teensy-tiny bit and a smidgen. Any more than a smidgen and stuff starts to die. Keep this as low as humanly possible without actually hitting zero. Realistically, the best way to deal with this is heavy planting as a first line of defense, or to do water changes and gravel vacuuming to get the poop out as a "oh shit my levels are climbing" kinda response.
| Ammonia mg/L and PPM | ||
|---|---|---|
| pH | Water Temperature 68F (20C) | Water Temperature 77F (25C) |
| 6.5 | 15.4 | 11.1 |
| 7.0 | 5.0 | 3.6 |
| 7.5 | 1.6 | 1.2 |
| 8.0 | 0.5 | 0.4 |
| 8.5 | 0.2 | 0.1 |
Warmer Tanks require less ammonia because it takes less energy for the bacteria to break down the ammonia into Nitrites.
Nitrites are bad. There is no purpose for them other to turn into Nitrates, so keep them at as close to zero as possible. They are moderately toxic to watercreatures, some moreso than others.
NITRITES - NO2 = 0 mg/l or PPM
Nitrates are what is eaten by plants eventually, which helps the plants grow and thus clean more, host more beneficial bacteria, and produce more oxygen to assist the watercreatures in having a nice home. These are only mildly toxic to watercreatures, and your levels should stay moderately low.
NITRATES - NO3 <= 30 mg/l
CO2 - Carbon Dioxide
Carbon Dioxide is very harmful to fish in larger quantities, but VERY good for plants. Just like on land, waterplants use CO2 to make O2 and use the extra C to grow a bit. However, since CO2 can be stuck into water, higher levels can kill your watercreatures. You don't need to test for this unless you are infusing CO2 into the water to help your plants, and even then, you usually will know when something happens because it will be fairly obvious. Cherry once left her CO2 on overnight and had a pretty bad shrimp dieoff. Tragic, but it happens to the best of us.
Temperature
The temperature of a tank is very dependent on what you have in the tank. Editor's Note - Ask Cherry the name of that cool fishkeeping method with no heater or filter Some tanks can run quite cold, some need to be closer to 78F, and this all depends of what kinds of watercreatures you have. The warmer the tank, the faster everything grows (including watercreatures), but the less margin for error you have with NH3, NO2, NO3 as the poop, pee, decay, and munching takes place faster. Also, algae will grow faster in a warm tank. Essentially, the warmer the tank, the more 'overdrive' your waterplants and watercreatures have.
Water Flow
Water flow, in traditional tanks at least, is EXTREMELY important. I had one of my loaches suicide in my filter which apparently clogged the pump and was putting out nearly no flow even on max setting. This caused a HUGE algae bloom in my tank and nearly spiked my ammonia due to the decay of the fish. I was able to catch it in time, however, but it is quite saddening to me because that means I need to both a) get a new filter, and b) make sure that I am checking the filter regularly for both flow and suiciders.
I know that flow is important to keep up at all times, but I do not know how important it is after you let the shit start to grow. Like, if you have a green algae bloom because your filter broke and you didn't realize 
, can you get back to the beginning by just scraping the algae, breaking up the brown algae, disturbing the detritus, and then running the filter at high flow for a while?
Another consideration is what kind of flow your watercreatures like. Betta fish prefer low flow, guppies like a medium amount. I have noticed in my tanks my neocaradinas prefer low to medium, but my ghost shrimp prefer as high as possible. Most snails don't care because they suction, and other watercreatures should be looked at on a case per case basis. You can tell if they are happy by their (stress line)[./fish.md#stress-lines] being visible or not.
Water Changes
It is important, if not running a lot of plants, during the initial cycling of a tank, in emergency measures, or just as a preventative measure, to change the water of a tank. The best way to do this is a gravity siphon to pull water out. Generally, do 1/4 to 1/3 of your tank for preventative maintenance and during cycling, or 1/2 if really freaking out about NH3, NO2, or NO3. When you fill the water back up, use a pump or a bowl, go slowly so as to not disturb the plant life, watercreatures, and substrate, and make sure to CONDITION YOUR WATER!
Treatment
Tap water needs to be dechlorinated in order to be safe for fish. There is a threshold where the chlorine level is 'fine' (though any is bad), and, if you have ever been to a pool before, you will know that some amount of chlorine offgasses into the air. Generally, if it is less than 2 gallons of water in a 15 gallon tank on occasion you can get away without treating it, mainly considering water topups. But, if you do a big water change (relative to the size of your tank), you NEED to treat the water with a dechlorinator. Check supplies for information on what to use.
Copper and Shrimp
Editor's Note - Ask Cherry TBD
Ick, Plagues, and Other Acts of God
Editor's Note - Ask Cherry TBD
Algae and Bacteria
Algae
Algae is really important for a proper tank setup, but too much is also not good! There are many types of algae, each with their own benefits and downsides.
Blooms
A bacterial or algae bloom can happen when there is an imbalance in the tank. Usually, this comes from algae buildup due to improper conditions, lack of bacteria, or too much fish poop causing the nitrogen cycle to completely one stage too quickly, with not enough stuff to clean the tank. The best way to get rid of an algae bloom is less light, often times by leaving the tank light off for a couple of days, or, in extreme scenarios, covering the tank with a blanket. If you do cover the tank, make sure to use a blanket that lets air in and out. If it would be too heavy to sleep under without getting 'CO2 air', it is too heavy to put over your tank. If you have a bubbler, this is mostly mitigated as it provides oxygen to the tank in place of air movement.
Biofilm (???)
Editors Note - Currently unsure if this is considered algae, need to ask Cherry
Biofilm is what grows on all living things when placed in the water. Biofilm is when the sugars in whatever organic material is in the water is broken down by bacteria and turned into cellulose and glucose. Generally this is a good thing, as it means that whatever you have in the water is acclimating properly to the underwater conditions, but if you have terrestrial plants beginning to grow aquatic roots (like a strawberry plant topper, for example), this is a bad thing as it signifies that the roots are dying due to not being acclimated properly.
As far as the normal biofilm for aquatic scenery and aquatic plants, the best way to deal with this is to add shrimp and/or snails! It is a food substitute for them, can sustain them for quite a long time, and also gives you something fun to look at (shrimpers call this 'grazing').
Filter Bacteria
When you have bacteria in your filter, it begins to smell. The smell of a filter can tell you a lot about the health of your tank. If the filter smells like fish, BAD! If the filter smells like wet dirt (like from a freshly watered garden), that's good! The dirt smell comes from the bacteria in the tank helping to complete the nitrogen cycle at a proper rate. Remember, the nitrogen cycle exists in the dirt too (where it is actually a lot easier/more common in small scale farming vs small scale fishkeeping) so there are a lot of parallels between gardening and aquariums. At the end of a proper tank cycling process, the filter SHOULD smell like dirt. If it doesn't, you either have problems with your tank, need to do some water changes, or your tank is not done cycling.