How to Fix Poor Water Quality

So, you’ve tested your water and found something off. Or maybe you’ve noticed a small slide in your previous recordings. How should you fix poor water quality without making things worse?

Ammonia Too High

This is the most common problems in most fish setups. As the primary fish waste, high levels indicate your filtration hasn’t been properly established, or there’s too much to process.

New Tank Syndrome

New tanks or ponds with unestablished filtration will all go through New Tank Syndrome. Your ammonia, nitrite and nitrate will go through the following stages as your system becomes “established.”

Over the counter “instant start” is not worth your money. If anything is even left alive in the container, the bacteria may not be right for your system. Long ago, it was thought only Nitrosomas and Nitrobacter spp. were responsible for your nitrogen cycle. Come to find that there are hundreds if not thousands of species that could be running the show, and not every system works best on the same bacterial mix. What works for your tank may not be the same as what works for the tank right next to it, your neighbor’s tank, your bosses’ tank or your online know-it-all’s tank. Plan ahead, don’t overwhelm your filter and take the 4-6 weeks to properly cycle your tank.

Overwhelmed Filtration

Your filtration may be established and working as hard as it can, but your ammonia is too high to get it down. This is usually the case with water that tests high for ammonia, nitrite and nitrate. There are two main causes of an ammonia to build up in an established system.

Underpowered Filtration

So you bought the 10-gallon filter for the 10-gallon aquarium; that should be sufficient, yes? Not usually. Depending on your bioload, factoring in what species of fish you have, how many fish you have, what they are eating and their activity level, you could be severely underestimating your filtration capability. We usually recommend most owners overestimate their filtration and select a system that is 1.5-2 times larger than their system. This will protect you against any unexpected hiccups.

Too Much Ammonia

Lots of fish being fed lots of protein equals lots of ammonia. Even if you have planned ahead with the supercharged filtration system, your fish may be producing more than your filter can handle at one time. Consider how many fish you have packed into your tank or pond. Do you have too many? Then, evaluate your fishes’ diet. Lots of protein = lots of ammonia. Are you feeding an appropriate level for your fish? Many times, owners will see a small ammonia spike switching from a “winter” to “summer” diet with higher protein.

Ammonia “Binders”

Chronic use of ammonia “binding” products will only hinder your efforts for proper filtration. If all your ammonia is bound up, what will your filter eat to survive? And how long is it “bound?” Depending on the method used by that particular manufacturer, your ammonia may come back to bite you. Rather than dumping in a bunch of chemicals, how about a nice water change instead?

Still have ammonia issues?

Check your source water. Sometimes, very small amounts of ammonia may be sneaking into your system with the new water. You may want to consider a first pass filter to get rid of some if it is a persistent problem.

Nitrite Too High

Thankfully, this one is a no brainer. It’s the same answer as above: you either don’t have your nitrogen cycle fully established or your filtration can’t keep up. If your nitrite is too high, you need to check your ammonia and nitrate levels to figure out which it is. If all of your parameters are increased, you have too much. No nitrate? You’re getting through new tank syndrome.

If you’re fish aren’t showing signs of stress from the high nitrite, don’t panic and figure out what you need to do to fix things. Too much nitrite can lead to brown blood disease, also known as methemoglobinemia. In this syndrome, the roaming nitrite binds to hemoglobin in blood, kicking off the oxygen. Your fish won’t be able to get any oxygen into its tissues and die. Thankfully, you can tell this grossly by the color of the gills. If you see brown gills, amp up the aeration and get your water chemistry fixed ASAP.

Nitrate Too High

If you have full conversion to nitrate, your nitrogen cycle is at least functioning well. However, high levels of nitrate can be just as toxic as high ammonia or nitrite, so let’s get your levels down!

Do Your Water Changes

Yes, “all natural” is a lovely concept, but it’s hard to obtain in a synthetic system. Most fish owners will need to remove the nitrates in their system BY HAND. For a tank, this means getting in there with a gravel siphon. For a pond, vacuum out those filters or do a backwash.

How Much Water Should I Change?

We recommend 10% weekly or 25% every other week, but you’ll know based on your nitrate levels. If they start creeping up >10 mg/L but less than 20 mg/L, it’s a good time to do a water change. Always remember percentages: if you do a 20% change in a system with nitrates of 20 mg/L, you’ve only reduced your nitrate to 16 mg/L.

Never do more than a 50% water change. It is too stressful for your fish. And if you have your fish in a bowl, you have other problems.

Add Some Plants

Plants are great at sucking nitrates out of the water and using it for fertilizer. However, sticking one little plant in a tank or pond isn’t going to make much of an impact. You are looking at upwards of 25% of your system to be dedicated to plants to make a significant impact in your water quality. You can always try out an aquaponic system. Grow some tasty veggies while you keep your water clean!

Algae will also use your excess nitrate. They love the free fertilizer and can be a big nuisance. Your nitrate levels may test okay, but your algae bloom will tell you the truth!

pH Too High or Too Low

And don’t think your pH is incorrect just because some guy on the internet said so! Here is a good resource for correct water quality parameters for all species. Except koi. Koi are happy in a very wide consistent range (see our reference sheet below).

Unless you have a super finicky cichlid species or saltwater tank, your main focus on pH should be consistency. A stable pH is a happy pH equals happy fish. For common pet fish, refer to our Water Quality Ranges.

Most problems with pH come from kH or alkalinity. kH measures the buffers in your water, and work hard to keep your pH stable. If your pH is off, check your kH and proceed below if your kH levels are too low.

The most important thing about incorrect pH levels is that you do NOT want to correct them quickly. A sudden pH swing is a surefire way to kill all your fish. “Slow and steady” is the name of the pH fixing game.

What is the best way to correct pH?

Do NOT do large water changes when faced with a pH discrepancy. 10% is enough. You can do them more frequently, however, up to every other day.

You do not need any “pH Up” or “pH Down.” If your fish can tolerate a wide range, don’t fight your source water. If you have a picky species, start with RO water and build the perfect water from the ground up.

kH Too Low

kH, not gH, measures the amount of buffers in your water. It is what keeps your pH stable, at whatever pH you have decided to maintain. Most kH comes from your source water. Unfortunately, this is a very important test that is not included in most “master” test kits. It is available separately, however!

If your source water is too low, you will need to add in extra by adding simple baking soda or commercial buffers. Keep in mind that a little bit goes a long way. Only add a little at a time and only add enough to treat the volume of water you change during a water change. This will keep your pH from swinging too much.

gH Too Low

gH measures the calcium and magnesium concentration in your water. It is part of your kH, but not all. In our area of California, unless there is a clear indication, I don’t even bother testing this any more because it is always too high.

Super high levels don’t cause many more issues than building up in your pipes. Some fish may get black speckles, which are tiny mineral deposits and don’t cause any harm. Do NOT try to scrape them off! You are just introducing more bacteria and disease.

Phosphate Too High

I don’t know why this is included in most test kits when it has ZERO impact on fish health. If your phosphates are too high, likely from your source water, expect to see more algae. That’s it.

Temperature Not in Range

Whether too high or two low, making temperature corrections is another case of slow and steady. Sudden temperature fluctations can stress your fish out and easily cause secondary disease.

Temperature Too Low

This is critical for tropical fish, such as bettas. We know it’s hard for little heaters to keep a small volume of water at a consistent temperature, but do your best. Sometimes, a little extra insulation with a towel can help keep them heat from fluctuating too much. Always use an reliable thermometer to keep an eye on your heater function.

Temperature Too High

For outdoor ponds, you are at the mercy of the elements. Thankfully, most koi and goldfish are hardy enough to deal with most temperatures, provided they don’t change too rapidly. If your pond is shallow, your temperatures will likely rise and sink faster.

If your pond gets a lot of sunlight and is shallow, it is critical to provide some shade. A sun sail or umbrella are easy to install and are not too much of an eyesore.

Indoor tanks suffering from increased temperatures are usually positioned in a poor location. Never put your tank in direct sunlight and keep it away from any heating or cooling elements, such as vents. If you have no other option, installing a light-blocking background or a simple cardboard sun block will help keep your temperature stable.

Salinity Out of Range

Ahh, the joys of marine systems. Salinity is critical for all marine fish, and some are pickier than others. Be sure you choose compatible species and check your salinity DAILY.

Salinity Too High

This frequently happens with systems that don’t have tight fitting lids or you’re topping off regularly with saltwater. Since these systems are heated, lots of water is lost to evaporation, but it doesn’t take the salt with it! Although your brain may fight you, always do your regular top offs with heater FRESHWATER. This is the best way to bring down a high salinity.

Salinity Too Low

Well, there is a chance of doing something too well. If you add too much freshwater, you may send your salinity the opposite way. It is unlikely, but this is why you check your salinity very frequently. If your salinity is too low, add a tiny bit of saltwater mix. Try not to add it to the tank directly, but make a supersaturated slurry and add it very gradually, keeping a close eye on your salinity.

Now you are all set to fix your poor water quality. Our best advice is to get a reliable test kit, replace it once a year and always log your results so you can see trends easily. Water quality is the #1 influence on fish health!

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