TDS question

[peewee1]

Is it possible that TDS could be 980? I ask because it makes me wonder if the meter that I am using should have a . point for a reading of 98.8 and not 980? HK is 40, ammonia .25, and ph is 7.6 following a water change. The tap TDS measure if 78 and the neighbor tank is 300 TDS. I think the meter is reading incorrectly.

[dspeers]

300 TDS is fairly high, 980 way too much, possible but crazy high for a fresh water tank. If you have questions in re your meter and a few spare dollars buy a Hanna TDS meter. Why is your ammonia not 0 and if it is truly .25 after water change then it is definitely in toxic range prior to water change. Hanna also makes a meter for that. If it's not obvious I like things that give me a numeric read out rather than a color to compare. KH 40? I assume that is ppm, very low and susceptible to rapid ph change. Low range for discus suggested around 70 ppm or 4dKH.

[peewee1]

300 TDS is fairly high, 980 way too much, possible but crazy high for a fresh water tank. If you have questions in re your meter and a few spare dollars buy a Hanna TDS meter. Why is your ammonia not 0 and if it is truly .25 after water change then it is definitely in toxic range prior to water change. Hanna also makes a meter for that. If it's not obvious I like things that give me a numeric read out rather than a color to compare. KH 40? I assume that is ppm, very low and susceptible to rapid ph change. Low range for discus suggested around 70 ppm or 4dKH.

The ph remains consistent at 7.6 to 7.8 month in and month out. I did a 50% water change now the TDS is 600 down from 980. I will change another 50 tomorrow.

[BrendanJ23]

I would find that strange. I have about 800 TDS(I increased it to that) in my pond that houses turtles, but they’ve got totally different requirements.

[bluelagoon]

Could it also mean that larger WC's are needed to your tank. As time goes by TDS and DOC should increase because of evaporation and small WC's over time. Seems with smaller WC's there are always some TDS and DOC left behind. Not being removed in large enough volumes and then a build up. I would think.

[peewee1]

Could it also mean that larger WC's are needed to your tank. As time goes by TDS and DOC should increase because of evaporation and small WC's over time. Seems with smaller WC's there are always some TDS and DOC left behind. Not being removed in large enough volumes and then a build up. I would think.

The TDS increased from 100 to almost 1000 in a matter of two three days. I thought water supply but coming from the tap it is 107. Within the past 12 hours the TDS has moved up from 600 to 623. This is 2 fish in 20 gallons. It must be a combination of several things. Fish bio waste, heater, or filters. One sponge filter and one external. Both cleaned within the past five days.

[coralbandit]

Anything in the tank like substrate or rocks ?
I agree with Mervin that the 15% daily changes is old tank syndrome issue waiting to develop .
Your math says you change 100% a week but is not really how it works .Changing only 15% leaves 85% of the crap behind to compound daily over a long time .
It is just math .
The 100 to 1,000 in 2-3 days would indicate something is leaching into the water ?
If the meter reads accurately from your tap I would suspect it is accurate in the tank also ?
I like HM3 TDS meters .Reliable ,cheap ,needs no calibration ..So cheap I have extras in case ...

[peewee1]

Anything in the tank like substrate or rocks ?
I agree with Mervin that the 15% daily changes is old tank syndrome issue waiting to develop .
Your math says you change 100% a week but is not really how it works .Changing only 15% leaves 85% of the crap behind to compound daily over a long time .
It is just math .
The 100 to 1,000 in 2-3 days would indicate something is leaching into the water ?
If the meter reads accurately from your tap I would suspect it is accurate in the tank also ?
I like HM3 TDS meters .Reliable ,cheap ,needs no calibration ..So cheap I have extras in case ...

HM 9001. I thought that something is leaching into the water. The tank water is the same tap water that the neighbor tank has. The neighboring tank is now 2 years while the tank in question is 2 months old. Same percent water changes both tanks same water. The older tank is 30 gallons with 4 discus, 2 cory, and a pleco now measures 300 TDS. The other tank is 20 gallons with two discus now measures 600 TDS. The only addition recent is a sponge filter. All else was in the tank when it last read 100 TDS last week. When the water was 980 TDS the fish were eating with no outward sign of distress. Theoretically if I should change another 50% today then the 623 TDS should drop into the 400 range. This worked for the neighboring tank read 500 TDS after several changes I have brought it down to 300 TDS.

[coralbandit]

Most articles say that Nitrates and Nitrites register on TDS meters ?
Did you test anything besides ammonia ?
I don't really test at all but if things get funny and clean water doesn't fix it pretty quick ,I go back and test for anything and everything till I see the issue?
Normally I just change water and it works so I never test anything but TDS when I add it .I don't use it to measure afterwards except in breeding tanks to keep track .
I think the water changes will help .

In the ideal world your tanks run even with your tap for TDS unless you are adding nutrients ...That just means large frequent water changes .
Leave 15% behind instead of just removing 15%..Your fish will thank you ..

[peewee1]

After roughly of a week of 40% water change I have managed to drop the TDS from 980 to 350. The neighbor tank is at 250 with the same tap water and with 30% daily water change. Tomorrow I would expect one tank following water change to be reading around 220 while the other at about 310 or so.

[dspeers]

NO2 and No3 both register on TDS meters, they actually measure electrical conductivity and estimate TDS from that value. That is why TDS is so much higher in a marine tank. I just do not get why you are seeing a TDS spike with less fish/gallon in your 20. Have you validated your TDS meter? Have you tested your nitrates? They should parallel your TDS rise, if not, seems something in the tank is dissolving, was that tank new when you set it up?

As an aside: Massive water changes always make me nervous. do 85% not 15%. Why? runs the risk of bigger pH, kH, gH changes, temp changes, microbubbles, multiple other ion swings. My goal is to remove the bad stuff but keep all of the good stuff as stable as possible. Understand I am not advocating for a lower total volume of water but if you decide that you want to change 50 % every other day, the math is clear, you remove just as much bad stuff (once the system is stable) changing 25% daily. Your trough value will be higher but your max concentration of whatever you are trying to remove will be the same. One caveat though, you start at the same time such that at 25% you change on D1, D2, etc, and with 50% you start on D2, D4, D6, etc. If you then do the math your max concentration will be the same in both tanks after a # of changes but your trough will be 50% your peak every other day vs 75% of peak daily. If you are worried about your average concentration which you may be with fry, then higher volumes are warranted, but I do want to maximize stability as stability=less stress=less disease, or so I hope. One caveat, you do need to remove the % by volume, not to a specific level in the tank or over time you will be changing less water than target due to evaporation.

Tom, what is your tank TDS target vs your source? I know what my Nitrate targets are but since I will be going with planted tanks nitrate levels are less reliable for tracking required water volumes. Also please don't take the above as any kind of criticism, just an alternative. Last thing I want to do is annoy you as I am so impressed with your success and can't wait to get some of your phenomenal rams once I finally get my tanks set up.

[coralbandit]

Tom, what is your tank TDS target vs your source? I know what my Nitrate targets are but since I will be going with planted tanks nitrate levels are less reliable for tracking required water volumes. Also please don't take the above as any kind of criticism, just an alternative. Last thing I want to do is annoy you as I am so impressed with your success and can't wait to get some of your phenomenal rams once I finally get my tanks set up.

I try to keep my TDS even with my source water . For grow out tanks with 100% tap that would be 350 TDS.
For breeding tanks it would be 100 TDS or lower.
When my breeding tanks get to 120 I change water [or sooner].
The tap tanks are usually more crowded and fed well so a TDS of 420 is not un common .
Smaller water changes leave some of everything that made the TDS climb still in the water where removing more then 50% of the water gets rid of at least half of the stuff.
The breeding tanks I set back to 100 and the grow out tanks go back as close to 350 as possible .
If I have not changed enough water I do a monthly [or more often ] re set where I change 90% of my water . That always gets the TDS back in line .
My source does not change much so it is a repeatable method and system I go by .I don't test for anything unless there appears to be some issue in the tank .
Evaporation can really bring TDS up pretty quick in my fish room .
Not annoyed ,I like to hear how all do it and see their outcomes . Their is more then one way to do things for sure , but when TDS is 2-3 times higher then source in a BB tank it is all in the water IMO .

[dspeers]

Tom, thanks much for the feedback, given your success you might want to make a sticky under waterworks as one way to systematically approach water change volume and frequency, there is a lot of commentary/recommendations without actual usable targets out there which is frustrating. Nitrates work well until they don't and there are several things that influence nitrate levels independent of overall water quality. I also looked at ORP as a possible target but got lost in what both the target and range should be so gave that idea up.

In fairness, my method is unproven, nothing more than my conclusions after reading everything I could find over the last 6 months. Plans for my system are on hold at present due to (mild) financial issues, new roof, two cars for college age daughters, two college age daughters, cost overruns on 67 mustang I am having to pay someone else to restore as I no longer can. Unfortunately on fixed income due disability , not a whine, actually pretty good but none the less.....fixed. Given that I need to minimize catch and carry on 5 gallon buckets I will be using an Apex system for routine automatic water changes which does have limits due to flow rates. Have the 2 125 gal displays, 65 grow out, and 45 hospital/quarantine tanks, apex system, 4 uv units, and 2 40 gal sump tanks, still need to add joists to first floor as well as plumb lines to all tanks from storage tank (currently in laundry room, but may move to basement). Philosophically I do worry about negative impacts of large water changes so would if requiring a reset probably opt for 40% and repeat in 2-3 hours for a 64% drop as opposed to changing 65% x 1. Hard for me to fully trust anything from NJ. Would be a waste of 15 gallons/100 which is a down side. Maybe I will test my source and if stable for several months/years change my mind.

[pablos]

my tanks various from 70 to 100 TDS (time to WC), since tap is below 70.

[Willie]

Most likely you have a water softener, which is adding sodium, potassium and chloride ions into the water to drive up TDS readings. If it's possible, tapping the pipe prior to the softener would be a better source for water changes. Note that FDA sets a maximum of 500 TDS for drinking water.