Knowing the Water in Each Tank

[Fish Folk]

A friend offered me some fish today. It was so generous! They are pretty uncommon in our LFS, and my mind began scrambling... (What can I move? What can I sell? How can I make this work?) 

What I know is that these fish need certain parameters to do well. I’m being non-specific here for a reason: this can apply to many species, many scenarios.  One tank option I’ve got would necessitate selling ca. 25 fish. Another option, though less water volume, would require only moving a few to another tank. But it’s water has had some different readings in the past. So... I ran a pH test.

Here’s the thing: I use the same tap (city) water for every water change, and I change out 30-50% every 1-2 weeks in every tank. 
 

I do the pH test, and it reads almost unchartably low... close to 6.0 pH. I go and test the other tank (with fish that would have to be sold). It reads  nearly 8.0 pH. On a lark, I test a third tank. It floats near 7.0 pH. 
 

I have explanations for each case, but the big thing I’m learning is that ... you need to know the water in each tank. It’s easy to presume, “My water is such and such... so my tanks are all pretty much thus and thus...” 

Unless they’re not! 

Edited March 6, 2021 by Fish Folk

[Brian]

Hmmm ,  so I have had 40 ish tanks at one time spawning a lot of different fish.  Currently I have only 6 up.  I have Angelfish, roseline barbs, neons, rummy nose, clown loaches, yo-yo loaches, African cichlids, some different gourami, guppies, and Discus.  You get the point.

  Unless I want the discus eggs to hatch I don’t adjust/test  my tap water.   In fact my test kit is old and I guess it should be replaced.   Is everyone happy and eating and for the most part making more (eggs or fry)?  Then I don’t mess with it. Now if you have that one odd ball or wild caught, then by all means you might need to adjust the water.  

[Fish Folk]

4 hours ago, Brian said:

Unless I want the discus eggs to hatch I don’t adjust/test  my tap water.   In fact my test kit is old and I guess it should be replaced.   Is everyone happy and eating and for the most part making more (eggs or fry)?  Then I don’t mess with it. Now if you have that one odd ball or wild caught, then by all means you might need to adjust the water.  

In all honesty, this reflects how we’ve thought too. We only test water if there’s a problem, or if submitting BAP reports. But there’s an assumption about all of our tanks that tacitly goes... “They’re not that different...” But maybe they can be? We like breeding projects, and frankly, it’s important to learn that our water is so variable that it can collapse or climb pH within days of being changed out. Obviously, we have soft water — little buffer. Limestone and crushed coral does its thing in one tank, while wood and plants do another thing in a separate tank. What I hadn’t calculated was how much a powerhead would accelerate chemistry. I’m no fan of chasing water parameters. Just roll with what you’ve got.

But then ... what if what you’ve got is enormously flexible? 

[Matt_]

I fully agree and have noticed that the tank water can change dramatically over time.  From my limited experience with only 3 established (seasoned) tanks there is a huge variation between parameters of the tanks as closed ecosystems.  These tanks all started at the tap pH and have shifted over time.  The more heavily planted tanks have a much lower pH as the growth has gotten denser.

Here are the pH readings from left to right:

Tap @ 54F - 7.4 (confirmed using high range)

65 gal planted @ 76F - 6.6

38 gal heavy planted @ 71F - 6.0

10 gal planted @ 77F - 6.2

 

[MJV Aquatics]

I'm just spitballing here, but if we trust the test results we need to look closely at the environments of each tank. You think that all your tanks should have very similar water chemistry. I've never found plants to alter pH so we need to consider stock levels, type and quantities of food, etc...I wonder if it's a gravel substrate and with rooted plants, it doesn't get gravel vacuumed so it becomes slightly acidic...sortof like what happens with  old tank syndrome?

 

[Fish Folk]

45 minutes ago, MJV Aquatics said:

I'm just spitballing here, but if we trust the test results we need to look closely at the environments of each tank. You think that all your tanks should have very similar water chemistry. I've never found plants to alter pH so we need to consider stock levels, type and quantities of food, etc...I wonder if it's a gravel substrate and with rooted plants, it doesn't get gravel vacuumed so it becomes slightly acidic...sortof like what happens with  old tank syndrome?

I think you’re onto some excellent clues here! Substrate, and how that gets treated with respect to water changes... also feeding and stocking... very important. How would you see the correlation between these factors? 

[Brandy]

I have the same situation--very soft, acidic, unbuffered water at the tap, dramtically different parameters from tank to tank. 

I think this is a great PSA: never assume you know what is happening with your water, CHECK.

[Hobbit]

This is a great reminder! I check my tanks before I move fish between them just in case the levels are really different. That’s how I learned that the gravel I got from Petco alters the pH in my 55 gallon. It’s the oldest and most heavily planted of my three current setups, and it has the highest pH (around 7.5). A tank like that, with soil substrate and huge driftwood, has no business being that high of pH! (My newish 10 gallon that’s moderately planted sits around 6.6-6.8.) In the 55, the plants are always starving for nutrients and the snails’ shells are not pretty, so I have no idea what it’s leeching into the water.