Water parameters - Some guidance please...

Morning everyone...

Relatively new to the hobby

I have a 1.2m (75G) tank with the following:
- 25 x mollies (Hard to count)
- 3 x cory's - 1 Pepper, 2 Salt/Pepper
- 1 x Bristlenose Pleco
- Plants basically just the hornwort (which I despise, will replace with something else at some point) and some other plants sold to me by LFS but cannot remember the name. Planted in the substrate.
- Internal filter
- 2 x Sponge filters
- 1 x 300w heater
- Few natural rocks and 1 ornament
- I run the tank at about 25'C-26'C depending on the ambient temperature.

In other words, a basic setup. Nothing fancy.

I used a Sera test kit for the last 6 months or so but I started distrusting everything it says because it almost always looked the same and within normal parameters. My tank seemed to struggle though. So last week I bough a JBL ProScan kit after watching a few reviews on Youtube and coming to the conclusion that it was indeed worth the buy.

Seeing the results (attached to this post) confirmed my expectations. The Sera kit must've expired or something. My PH, especially, is of concern and I need to sort this out.

I have a RODI system. I know I can't just use the RODI water in the tank as the required minerals aren't present.

So I have two questions:
1. If I were to do a 90-100% water change, what products could/should I use to remineralize the water and in what measurements/quantities?
2. If I were to only try and fix the water parameters of the water in the tank, what should my course of action be?

 

Some quick thoughts on solving the problem:

1. I would go for 50% changes maybe 4-7 days apart and monitor the levels until they get to where you need them. Especially those nitrate and nitrite levels. I'd avoid doing a full water change to maintain some sense of stability.
2. If you're in Cape Town you can use the tap water - treat with Seachem prime and leave standing for a day or so.
3. For regular maintenance of the parameters your solution would likely be more regular water changes without knowing more - say 20-25% weekly based on the livestock in the tank - if you are not doing that already.

That's what I would do, but I've only come back into the hobby now after a decade break so my knowledge could be out of date.

Some questions which could help the community understand your predicament better:
1. How often do you change the water normally?
2. The pH value is very low for a tank without CO2 injection - are you using a mix of tap and RO when you do water changes?
3. Are you losing livestock regularly?
4. I'm also curious about the chlorine being detected in the first reading? Did you add tap water prior to that reading?

 

@Fredster Thanks for the reply...

1. Probably once every 2-3 weeks. About 40 litres or so.
2. Only got the RO thingy recently (in prep for the saltwater setup I want to do at a later stage - buying everything in bits and pieces to spread out the spend) so haven't really used it too much. When I do use it, I take the wastewater + the RODI water and combine it. The TDS then sits at around 30-40 ppm. Before that I just used normal tap water and treated it with JBL Biotupo to keep the chlorine levels low as possible.
3. Lost a Khune loach over the weekend (was a new inhabitant that didn't last a day - guess it's because of the water values I just posted)
4. #2 probably answers your question.

 

Ja, so my best guess at your solution is that you need to do the following:
1. Drop the RO water for your freshwater aquarium, only use tap (because CT water is already very soft).
2. Change weekly rather than 2-3 weeks.
3. Change 60-80 litres when you do regular water changes. Preferably dechlorinate before it goes into the aquarium.
4. Until you get your Nitrites/ Nitrates down to acceptable levels do 50% water changes every 4-7 days.

I was horrifically bad at chemistry so I'll leave it to the experts here to explain in detail but from the info given your problem is being caused by the combination of very soft water (0-3 dKH) combined with too infrequent/ too little water changes.

Good luck!

 

That all makes sense. Thanks @Fredster

So Seachem Prime as the de-chlorinator, right?

 

Correct.

 

I think completely replacing the water in the fish tank is a not-so-good idea. This is because it will remove beneficial bacteria that live in the tank and reset the nitrogen cycle, which could kill your fish. Doing a partial water change once or twice a month is the most effective option if you regularly clean your tank. With a water hose, bucket, and water vacuum, you can achieve a 100% change in your home. At the beginning, remove 50% of the water using a vacuum. Do not clean a lot of substrates. It is recommended that you clean the substrate 2 weeks before you change your water to 100% if you want to do that.
It is then necessary to fill the tank with 50% water that has been treated with prime or another conditioner. This water should be brought up to about 78 degrees around the middle. You can use your bucket for this.
You can keep repeating this process a total of 3–4 times and almost all water is cycled without much stress. With a hose, you can do this easier by filling and cleaning at the same time. This is once you have practiced when and how much prime to add and if your tap water is about the same PH. And temperature.
I tried it successfully and luckily had success. Don't lose any fish or cause stress to them. I also use a little bit of API stress coat in these situations. As an extra precaution, if you are a bit paranoid, you can add API quick start nitrifying bacteria, or tetra, whatever you prefer. Adding too much bacteria is never a concern, so you can even add the entire bottle. However, that's overkill. Having sponge filters and other filters would preserve enough bacteria to trap ammonia for 24 hours. Any fresh ammonia that would be injected into the system at this point would have plenty of time to be cleaned.
The quality of your tap water will play a significant role here as well. Use bottled water from LFS if it has too much ammonia or chloramine in it or stick to a maximum 50% water change if there is too much ammonia or chloramine in it.

 

@techedemic how are you coming along with your aquarium?


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