Nitrates up, pH and total alkalinity down

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Aquarium Advice Newbie
Apr 15, 2024
Williamsburg VA
Newbie first post! I've had my tank for over a year, and it NEVER seems settled. I feel like I'm constantly chasing equilibrium so what I intended to be a calming addition to my office is a constant stressor...:( I've had a few friends trying to "help" but I just get more and more frustrated.

Currently, I have the issues listed in the title. I've just been using the test strips so I don't have numbers (ordered a master kit this weekend after reading some blogs). In addition, the water is a smidge cloudy, although it is better than it was on Friday.

My current friends seem ok (2 mollies, 3 neons, 1 zebra danio, 1 glo danio, 1 red striped danio(?), 1 black tetra and 1 white skirt tetra) in a 29 gallon tank. I would like to get a few more friends for those that are solo and 2-3 bigger, but don't want to add until things are straight.

I did a vacuum/water change a couple of weeks ago and changed the filter at the same time. Now I'm reading that may not have been a good idea.

So, lots of words to ask: 1) what can I do to fix the current issues (without alot of chemicals if possible), 2) what is a good cycle for vacuum/filter change/water change, and 3) what chemicals should I use after changes (if needed)?

I appreciate any help I can get.
Without numbers its a little difficult to be precise, but here is some general information.

Mollies tend to like harder water with a higher pH. Tetras tend to prefer softer water with a lower pH. Danios are going to prefer it somewhere in between. However fish can acclimate to a wide range of water parameters, and if youve had the fish for over a year with no problems, i wouldnt go trying to mess about with the water. Without seeing numbers, i dont see any issues that need resolving.

Nitrate is going to make the water more acidic and lower pH, KH acts like a buffer and absorbs acid, stopping the pH falling. If your KH gets too low your pH will drop, until you do a water change, that replenishes the KH and stabilises the pH again. For most people a regular water change will keep your KH at a good level, and keep your pH steady. Without knowing where your pH and KH is, both out of the tap and in your aquarium, its difficult to say if you have an issue, but again nothing you have said so far gives any concern.

Nitrate can get quite high without becoming toxic for fish. Lower is better, but 40ppm is commonly considered a good upper level, and many people successfully keep fish at higher levels than 40ppm. Without knowing what your nitrate is at, its difficult to say if you have an issue, but again nothing you have said so far gives any concern.

Water change schedules generally get done to control nitrate to keep it below that 40ppm target. If a weekly 50% water change doesnt keep you below that 40ppm you should consider you may have too many fish. Your number of fish is quite low for the size of your tank, so i would expect a 30% to 50% water change every 2 weeks would be sufficient, but knowing nitrate would help to fine tune this. Water changes also replenish other minerals, like GH and KH, so if you have soft water you might need to do water changes more often. A weekly water change is always a good idea even if your parameters dont always say its needed.

The only chemical you need is water conditioner. Use a water conditioner every time tap water goes in your aquarium. Seachem Prime or API Aqua Essential would be my recommendations, based purely on cost/ water change. If your water is treated with chloramine rather than chlorine make sure whatever you use treats chloramine, but they pretty much all do nowadays.
Thank you so much for all the information! As soon as I have the test kit in hand, I will be able to give numbers. One thing of note, I've been using distilled water (water purifier on home tap, so I bring from there). Is this better/worse/doesn't matter?
Distilled water will have no mineral content, so zero KH. With no KH natural acidification will cause the pH to crash. It would also cause some other issues that would be very apparent that you are actually reporting the opposite of. So getting some water parameters would be useful.

People who use distilled or RO filtered water need to remineralise it.

How are you obtaining your distilled water? What do you mean by a water purifier? Are you meaning like a Brita filter or a water softener?
It's actually RO water; a 3 gallon filtration system attached to our kitchen sink.
That water would need to be remineralized in order to add any carbonate hardness (KH) to it. It's KH that helps buffer your water to keep the Ph from falling. As explained, when there is no or low KH, a rise in nitrates causes a drop in Ph. When the Ph reaches levels under 6.8, nitrification slows down. Under 6.0 and nitrification virtually stops entirely. If it stays under 6.0 for too long, the nitrifying microbes die off so you would need to cycle the tank all over over again if you raise the Ph to a more "proper" level.
If your RO is working correctly, then it should have zero KH/ alkalinity coming out of the filter (or at least very little). As well as buffering against pH drops, KH/ alkalinity is consumed by the microbes that cycle the tank. If you have zero KH/ alkakinity you have no cycle. If you have no cycle, you get no nitrate.

But, you are reporting that your nitrate is rising and KH/ alkalinity is falling. So that doesnt make sense if your water is RO filtered because neither of these things should happen.

When was the last time you had your RO filter maintained? Are you sure its working properly?

Is there a reason you cant use unfiltered tap water? Most people use tap water for freshwater fish just fine.

If you are using RO going forward, you might want to consider getting some remineralising salts like Seachem Equilibrium for GH and Seachem Alkaline Buffer for KH/ alkalinity. That way you can really dial in your water to the parameters you want.

But, having said all that your fish are fine. Not mucking about with water if there is no need is almost always the best way forward.
Thanks for all of this help/knowledge! I just received notice my new kit has been delivered, so I should have actual numbers tomorrow and will report back.

Update: Forgot to answer the question about RO water. I started using it on recommendation from a friend, but I'm no longer confident she has the knowledge base I need, since I have gotten to a happy place after so much time. :)
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The master test kit doesnt include the tests for KH or GH which will tell you if you need to address hardness. But let us know what the test results are from what you can do. Would be useful to know what your aquarium is at, and what your RO water is at.
Good morning! I'm back with some test results, and wish I could change my title to this string since it's COMPLETELY wrong! :-(

Here are my results on three different water sources:

pH = 7.8
Ammonia = 0
Nitrite = 0
Nitrate = 40-80 ppm

RO water available:
pH = 6.4
Ammonia = 0
Nitrite = 0
Nitrate = 0

Tap water available:
pH = 7.0
Ammonia = 0.5
Nitrite = 0
Nitrate = 0

So, I'm not sure if my tank numbers are ok or need adjusting. Based on the information on previous responses, I think I would be ok using the tap water here at the office instead of lugging RO water from home.

Ready for suggestions!
Your nitrate is high in your aquarium. What has been your normal water change schedule?

The pH in the aquarium is much higher than the water you are using for water changes. This will be due to disolved minerals getting into the water somehow. Are you adding anything like a mineral buffer or baking soda? Do you have a rocks that might be disolving that might be calcium carbonate, like limestone?

From your test there is nothing wrong with the tap water. You are only testing for what the test kit has tests for however. The only minor issue with the tap water is the presence of ammonia. The ammonia is likely caused by the presence of chloramine, which is an alternative treatment to chlorine.

Chloramine is chemically bonded ammonia and chlorine. Its more stable than chlorine, so its becoming more commonly used by water companies. Unfortunately for fish keepers, its an ammonium source.

Water conditioners that treat chloramine will break the chemical bond, separating the ammonia and chlorine. The water conditioner will also remove the chlorine, leaving just the ammonia. So when you use chloramine treated water for water changes, your water is going to introduce some ammonia, and ammonia is toxic for fish. In a cycled tank, the nitrogen cycle will consume the ammonia in short order ultimately turning it into nitrate which you remove with your regular water changes as normal.

Some water conditioners will temporarily detoxify ammonia for a couple of days. Seachem Prime or API Aqua Essential will do this, so i would use one of these as your regular water conditioners. The detoxifying property of one of these 2 water conditioners will make the ammonia non toxic until your cycle has had chance to consume it.

If you plan on switching from RO water to tap water, i would do several small water changes over several days. Say 10 to 15% per day for a week. That way the change in water types will be gradual and less of a shock to the fish. And then settle into a regular water change, which should be more frequent, or bigger, than what you are currently doing.
I haven't had any real water change schedule; I've just been doing when the water looks cloudy or the algae gets to be too much for me.

The only additive I've been using is Top Fin water conditioner (based on the dosage on the bottle) with any water added or changed. Based on your recommendation, it seems I should be using Prime (I used when I started up the tank) or Aqua Essential based on the test results for my tank.

Once I've done the small water changes you suggest to switch back to tap water, what schedule would you recommend for water changes, filter changes and vacuuming? Should they all be done at the same time, or should they be staggered?

This has been so hopeful!
Let us know where your parameters are after the week of small water changes.

But id then see how things are after a month of 30% weekly water changes. If you test immediately before your weekly water changes and its in the 20 to 40ppm range, then 30% weekly is your new schedule.
"Once I've done the small water changes you suggest to switch back to tap water"
I think he is saying go ahead and use tap water and do your small changes with that to introduce it slowly.

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