TDS is it needed .

[skar]

so went to a fish store, asked about their ph range for their fish .
The gentleman asked about my TDS on my tank. I never tested them before.

I purchased one supposedly pre calibrated . My main tank was 770 and my small betta tank was worse 880 !!
Tap measured 440. I did water changes which got them down to 600s.

But is TDS significant for anything? I mean so they are high, does that automatically make it stressful on the fish??

Ide really prefer not to spend 1000s on water changes and filters, RO or H20 softener :/

 

[ruud]

95% of our hobby fish live in waters that can be placed on a scale from negligible mineral water (blackwater) with a TDS of <40, to soft water with a TDS of 40 - 150, up to hard water with a TDS in the 100s.

The main minerals in these soft to harder waters are by far calcium (GH) and carbonate (KH). You can confirm this for your source water.

Hence, although TDS cannot inform us about the mineral composition, if you know your source water and know a thing or two what happens to minerals in different aquarium setups, TDS is a very quick and easy proxy.

I conduct water changes solely on basis of TDS.

If TDS surpasses 40 in my blackwater tank, I conduct water changes to bring it back to 20.

Why would I measure pH in my blackwater tank? It is very likely to fluctuate between 5 and 6. It never gets to 4 and it never gets to 7, provided I keep the TDS low with RO water.

Why would I measure ammonia or nitrates in my blackwater tank? There is always one or two plant leaves turning yellow. Nitrogen must be scarce.

I can continue this line of reasoning for heavily planted tanks.

Bottomline, TDS is very handy if you understand and apply a few other indications. But this is or should be no different from pH. A pH value only becomes meaningful when it is considered in relation to other water parameters and conditions.

 

[cdr63corv]

I pay close attention to my tds when breeding my discus. Much over 120 and the eggs don't hatch with my water. Otherwise I really don't pay attention but the highest any of my tanks run is 190. Not sure what it means with numbers as high as yours. I know substrate and different types of rocks can affect the numbers.

 

[MasterPython]

The number itself is not useful without context from past readings and other water tests. It can't tell the difference between salts, minerals, nitrates or other things in the water but you can quickly check if the number is going up or down over time.

 

[tinylostwine]

Bottomline, TDS is very handy if you understand and apply a few other indications. But this is or should be no different from pH. A pH value only becomes meaningful when it is considered in relation to other water parameters and conditions.

I would argue that TDS is more important than PH esp since PH can easily fluctuate for reasons that are unrelated to fish health and care. I would also argue that for those of us who deal with ultra low TDS the composition of kh/gh becomes irrelevant. However for higher value of TDS yes it is useful to know the break down of kh/gh.

There are some issues around ph that have more to do with the type of bacteria that forms in the aquarium at the extreme end and you certainly don't want to subject fishes to constant changes in bacteria due to ability of the fish to generate immunity so some stability is necessary but daily fluctuation in ph isn't really going to play a role here.

Of course i am talking about the low end of the scale and there are fishes like lake Malawi that are on the other end of the scale.

There is also some but limited research on how hardness impact fish health with some requiring harder water then others.

Anyway the simple answer to your question is yes it matter but i would also be concern about why your tds is rising in the aquarium as that probably indicate something in there is leaching which is always a bad thing (imho) though sometimes it is intentional.

 

[Gnop1950]

I personally only use TDS to track trends. My tap water is consistently between 180 and 190 TDS. My freshwater aquariums are usually around 350 - 450 TDS. The only exception is my Betta Tank that I started with remineralized RODI water.

440 TDS from the tap is relatively high in my experience, but not critically so. It depends on what is contributing to the high TDS.

Without using RODI water, 440 TDS is your floor if that is your tap water reading. Assuming your TDS meter is correct, a rise of 100-200 TDS in your tanks seems reasonable to me.

A good way to minimize the rise in TDS is to use RODI water for top-offs. Small RODI units suitable for top-offs are relatively inexpensive. I have 2 x 5-gallon jugs I keep filled with RODI water just for topping off my aquariums.

All of the fish in my aquariums are captive-bred and, in those cases where I know the water parameters like pH, were raised in water that is often quite different than that of their ancestors. My Angelfish, Rummynose Tetras, etc. were purchased from a dealer whose pH is around 8.3, and both KH and GH are over 300 ppm each. With numbers like those, I'd guess the TDS is likely way up there as well.

Fish are very adaptable. I had a Corydoras breeding explosion in a tank where the TDS was around 425, and the pH was at around 7.6-7.8.

If your fish are healthy, stability is much more important to me than any particular number. If your other water parameters are good, I personally would consider a small RODI unit for top-offs to try and keep your TDS within, say, 100 ppm of your tap water.

 

[skar]

I personally only use TDS to track trends. My tap water is consistently between 180 and 190 TDS. My freshwater aquariums are usually around 350 - 450 TDS. The only exception is my Betta Tank that I started with remineralized RODI water.

440 TDS from the tap is relatively high in my experience, but not critically so. It depends on what is contributing to the high TDS.

Without using RODI water, 440 TDS is your floor if that is your tap water reading. Assuming your TDS meter is correct, a rise of 100-200 TDS in your tanks seems reasonable to me.

A good way to minimize the rise in TDS is to use RODI water for top-offs. Small RODI units suitable for top-offs are relatively inexpensive. I have 2 x 5-gallon jugs I keep filled with RODI water just for topping off my aquariums.

All of the fish in my aquariums are captive-bred and, in those cases where I know the water parameters like pH, were raised in water that is often quite different than that of their ancestors. My Angelfish, Rummynose Tetras, etc. were purchased from a dealer whose pH is around 8.3, and both KH and GH are over 300 ppm each. With numbers like those, I'd guess the TDS is likely way up there as well.

Fish are very adaptable. I had a Corydoras breeding explosion in a tank where the TDS was around 425, and the pH was at around 7.6-7.8.

If your fish are healthy, stability is much more important to me than any particular number. If your other water parameters are good, I personally would consider a small RODI unit for top-offs to try and keep your TDS within, say, 100 ppm of your tap water.

Thanks
My ph is stable at 7.0 with the almond leaves I’ll look into the smaller r/o units .

I do use playsand for substrate, it’s been in there for more than 7years I don’t really know if that’s contributing or not.

The gh is off the charts high in my water even from the tap.

 

[TClare]

Remember that TDS does not just measure hardness, if nitrates build up this will also cause TDS to increase. In an unplanted tank TDS can increase between water changes, while in a densely planted tank it usually decreases as plants use up the minerals and nitrates. I have no experience with high levels of TDS, my tap water being under 20, and tanks rarely above 30, usually around 22 ish.

 

[skar]

I posted this on a similar platform and so far the consensus seems to be that I really shouldn’t worry about tds readings, mainly because they are not specific and just aim for stability in the aquarium.

 

[MasterPython]

I posted this on a similar platform and so far the consensus seems to be that I really shouldn’t worry about tds readings, mainly because they are not specific and just aim for stability in the aquarium.

Some fish and shrimp need soft low PH water that is achieved by using RODI water and a TDS meter is a great tool for maintaining it.

It sounds like you have hard tap water which is much easier to keep stable because the minerals buffer the PH and the mixture of minerals remains fairly consistent if your city uses the same water source all the time. Most freshwater fish are captive bred in harder water than they have in the wild and have no problem living in it.

 

[tinylostwine]

I posted this on a similar platform and so far the consensus seems to be that I really shouldn’t worry about tds readings, mainly because they are not specific and just aim for stability in the aquarium.

So this is not exactly true - there are extremes. TDS is calculated based off of electrical current and is an estimate. There are many things that can cause TDS to go up such as decaying leaves, nitrate, ....

So if we talk about TDS 80 vs 120 without additional information it is difficult to determine if the difference is significance or not (and this also applies to very delicate fishes that require very soft water).

However if we talk about for example 800 tds which is an extreme number while we don't know the exact cause of the TDS we can almost guarantee that any fish that thrive in soft water such as cardinal tetra or harlequin rasboras will suffer and have noticeable shorten life span.

Conversely a hard water fish such as those from Lake Malawi will almost certianly die over night or within a few days if the TDS 50.
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So some information can be obtained from just a TDS reading. Also if your aquarium jumps from 300 TDS to 600 TDS in a week then something in the aquarium is likely leaching which depending on the type of fish you keep is probably bad.
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However if you want a more precise understanding then yes further analysis of the water is necessary such as measuring gh/kh/nitrate and ultimately you might even need a full lab analysis depending on the TDS value and the value of the other easily measured components.
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It is normal for an aquarium TDS to drift up over time simply because nitrate and other waste builds up in the water but that doesn't mean TDS is useless you can still determine a lot by the rate of gain over time.
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Last but least as mentioned by MasterPython if you keep a lot of 'blackwater' fishes (fishes that require extremely pure water) even slight rises in tds can be an indication of a problem. After all if your tds needs to be in the 10 range the amount of minerals in the water is so low it matters not if the traces are gh/kh/nitrate or whatever.
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So TDS is not totally useless nor can it be ignore.
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People like to say fishes are adaptable and keeping cardinal tetra is fine in 800 tds water but what they really mean is that if you live in a region of extremely hard water and the store has some cardinals you can probably get away with buying them and they won't instantly die but that doesn't mean they will live long healthy lives more so if breeding is the sort of thing you like to do with fishes cardinals are not going to be able to breed in 800 tds water regardless of the composition.

 

[TClare]

So yes, ir is important to know the TDS when deciding what fish are most suited to your water. Also it’s very quick and easy to measure TDS, much quicker than doing all the other tests, and depending on your aquarium situation it will probably be easy to deduce whether any increase over time is due to nitrates building up, or that something is leaching into the water from substrate or rocks, or if you’ve been adding fertilizer etc. A TDS pen is also useful for measuring temperature.

 

[ruud]

I posted this on a similar platform and so far the consensus seems to be that I really shouldn’t worry about tds readings, mainly because they are not specific and just aim for stability in the aquarium.

Stability of what? Life follows patterns, mainly driven by the sun: day-night, the seasons. Hence, light intensity, temperature, pH and even TDS (through biological activity and weather conditions) fluctuate in patterns.

Yet, for example, our cheap aquarium heaters follow a pattern that crosses this logic, not making any difference whether it is noon or midnight, summer or winter.

There are anecdotes that prove all sides, backed-up by the rationale that "these are captive-bred fish that have adapted".

Typically anyone searches for answers that match their initial ideas.

Is TDS needed? Is KH needed? Is stability needed? Are water changes needed?

At least, TDS is a very quick and easy measurement to manage a tank, from setting one up, to determine the frequency and extend of water changes, and to prepare the source water (determine what TDS value matches grams of GH or KH salt, and reuse the number forever when preparing water given X volume).

If you only apply this method (TDS pen and very likely a RO filter) you might open up a much more relaxed approach to aquarium maintenance.

I truly have no idea what the pH of my tanks is, but I'm sure it fits the circumstances.
With or, in my case, without carbonates/KH.

 

[skar]

It’s just hard Gh water and likely plant matter. I know it’s not nitrates, the fish and shrimp are thriving .
I’ll keep stability going and not worry about TDS.
It’s irrelevant to track, I’m not planning on running a r/o system.

Appreciate everyone’s advice.