Question regarding low TDS

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cresnyk

cresnyk

Plecostomus
MFK Member
Jun 5, 2011
103
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CLAYTON, NC
I've recently been doing a bit of research on TDS/conductivity because I've seen that a lot of ray keepers are using reverse osmosis filters on the water they are dripping into their set-ups. This got me worried that I have not been monitoring my TDS values at all and have never really given it any thought.

So, I purchased a TDS meter to monitor the values on my tanks. First measurement out of the box was on molecular grade deionized water. As expected, TDS = 0 ppm. I then took a measurement on bottled water which came back at 63 ppm. Next up I measured the water dripping into my tank from my well. TDS = 49 ppm. Subsequent measurements of a tank on the drip and another not came back at 68 and 90 ppm, respectively.

I'm fairly confident in these measurements, but have ordered standards (https://www.amazon.com/Conductivity...words=conductivity+calibration+solution&psc=1) to make sure that I'm not orders of magnitude off or anything like that. Even tolerating a +/- 10% error, these readings are quite a bit lower than those being reported by others.

This brings me to my question: should I be remineralizing my water or supplementing my tanks? If so, what products should I be looking into?
 
It's tough to say because you don't know what DS are in your TDS. A little marine salt would add plenty of ions though. Just don't go over 2-3ppt as it will impact your biofilter.
 
Pomatomus said:
It's tough to say because you don't know what DS are in your TDS. A little marine salt would add plenty of ions though. Just don't go over 2-3ppt as it will impact your biofilter.
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Just out of curiosity, can anyone see this having a negative effect? Adding 2-3PPT marine salt will bring my TDS reading up over 2 to 3000 ppm, respectively. From my understanding of what I've been reading, people have been trying to keep TDS values quite low. Is this because of concern for having the 'wrong' DS in the water? Are the DS from marine salt the 'right' DS to have at higher concentrations?

Unless I'm missing something, I'd be more comfortable bringing my TDS up to .2-.3 PPT using marine salt. Perhaps I'm making this more difficult than it needs to be.
 
That would be absolutely fine. 2-3ppt is just a maximum. When people add salt to combat nitrite poisoning they only have to add a few ppm! Having ions in the water is good for the fish as it helps their osmotic balance. Freshwater fish are constantly drinking water and peeing it out in order to sequester ions. Saltwater fish try not to drink water and do not pee much as they have less ions in their bodies than the surrounding water.

Typically TDS is used when filtering water through reverse osmosis. You want as close to 0 tds as possible so that you aren't introducing unknown, unwanted chemicals to your corals. Then salt is added to this water to replenish the proper amount of minerals. I don't keep rays, but I know that like most Amazonian fishes they require soft, acidic water. I'm sure they would appreciate a low TDS, but again it depends exactly what we're talking about in terms of solids. I would recommend watching your alkalinity,pH and hardness more than your TDS.
 
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Pomatomus said:
That would be absolutely fine. 2-3ppt is just a maximum. When people add salt to combat nitrite poisoning they only have to add a few ppm! Having ions in the water is good for the fish as it helps their osmotic balance. Freshwater fish are constantly drinking water and peeing it out in order to sequester ions. Saltwater fish try not to drink water and do not pee much as they have less ions in their bodies than the surrounding water.

Typically TDS is used when filtering water through reverse osmosis. You want as close to 0 tds as possible so that you aren't introducing unknown, unwanted chemicals to your corals. Then salt is added to this water to replenish the proper amount of minerals. I don't keep rays, but I know that like most Amazonian fishes they require soft, acidic water. I'm sure they would appreciate a low TDS, but again it depends exactly what we're talking about in terms of solids. I would recommend watching your alkalinity,pH and hardness more than your TDS.
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Thank you! I appreciate your feedback. Slowly adding parameters to my testing scheme. I'll stick to measuring TDS only on water entering my system. GH and KH test kits are on the way.

As most do, I've tested pH since I began fish keeping. My water coming from my tap is soft, generally ~6.5-6.8 pH, and this is buffered to 7.4-7.5 by the substrate in my systems.
 
cresnyk said:
Thank you! I appreciate your feedback. Slowly adding parameters to my testing scheme. I'll stick to measuring TDS only on water entering my system. GH and KH test kits are on the way.

As most do, I've tested pH since I began fish keeping. My water coming from my tap is soft, generally ~6.5-6.8 pH, and this is buffered to 7.4-7.5 by the substrate in my systems.
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How long has your system been running? What size, how many fish in the system?

Imo you have a good thing working for you. I wouldn't change a thing. Sounds like you have a great makeup water, if i had that i would not be dripping RO, i would use it as is. Maybe run it through a sediment and carbon block first but not an ro membrane, i dont think you need it.

If your system pH starts to drop off lower than what your drip water is I would make a change. Like adding calcium carbonate (crushed coral) into the system to keep buffer. You mentioned already though that your substrate buffers your water, are you using a cc or aragonite substrste?

I would personally not add marine salt constantly to a fw ray tank. Tresting for something is one thing... Rays tolerate salt pretty well for short periods of time if healthy, but long term salt in high quantity can have detrimental effects on biological filtration and rays. I have seen this first hand.
 
SHARK13 said:
How long has your system been running? What size, how many fish in the system?

Imo you have a good thing working for you. I wouldn't change a thing. Sounds like you have a great makeup water, if i had that i would not be dripping RO, i would use it as is. Maybe run it through a sediment and carbon block first but not an ro membrane, i dont think you need it.

If your system pH starts to drop off lower than what your drip water is I would make a change. Like adding calcium carbonate (crushed coral) into the system to keep buffer. You mentioned already though that your substrate buffers your water, are you using a cc or aragonite substrste?

I would personally not add marine salt constantly to a fw ray tank. Tresting for something is one thing... Rays tolerate salt pretty well for short periods of time if healthy, but long term salt in high quantity can have detrimental effects on biological filtration and rays. I have seen this first hand.
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I appreciate your feedback. This system has been running since early March. Tank is a 300 gallon 6'x4'20" with a 50 gallon sump containing 50L fluidized K1. Currently housing 2 rays 7-9" disc.

I was looking into RO prior to testing my TDS. Pretty obvious now that RO isn't necessary. Would something like this still be beneficial?:

I have ~100lbs caribsea torpedo beach in the tank. The reason I was thinking that its buffering the water is that my aged tap water has a pH in the mid 6's and the tank holds pretty steady at 7.4-7.6. I measured kH and gH for the first time today which came back at 53.7 and 71.6 ppm, respectively.

My concern was that my values are TOO low. I know that guys dripping RO water are dripping in part tap water as well. I don't have that option to bring my values up. Should I be concerned with water entering my tank having TDS < 50, and if so, what should I be adding? I was considering having a full screen run on my tap water by a local lab, but I'm not really sure what I'm looking for?

My rays are in good health. Active. And I generally feed 3-5 times per day. The reason why I started concerning myself with TDS values is mostly because I've seen vamptrev vamptrev and DB junkie DB junkie reference TDS values as an indicator of water quality several times. I was hoping to use TDS as an indicator of when to do water changes, but it would likely take several weeks for my tank to reach levels over 100ppm.
 
Consistency is key. Sounds like you are in a good place right now. Low tds is good, but sounds like you may have low kh since your aged water is 6.? Ph. What is your tap ph?

What you want to stay away from is large fluctuations.
 
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cresnyk said:
I appreciate your feedback. This system has been running since early March. Tank is a 300 gallon 6'x4'20" with a 50 gallon sump containing 50L fluidized K1. Currently housing 2 rays 7-9" disc.

I was looking into RO prior to testing my TDS. Pretty obvious now that RO isn't necessary. Would something like this still be beneficial?:

I have ~100lbs caribsea torpedo beach in the tank. The reason I was thinking that its buffering the water is that my aged tap water has a pH in the mid 6's and the tank holds pretty steady at 7.4-7.6. I measured kH and gH for the first time today which came back at 53.7 and 71.6 ppm, respectively.

My concern was that my values are TOO low. I know that guys dripping RO water are dripping in part tap water as well. I don't have that option to bring my values up. Should I be concerned with water entering my tank having TDS < 50, and if so, what should I be adding? I was considering having a full screen run on my tap water by a local lab, but I'm not really sure what I'm looking for?

My rays are in good health. Active. And I generally feed 3-5 times per day. The reason why I started concerning myself with TDS values is mostly because I've seen vamptrev vamptrev and DB junkie DB junkie reference TDS values as an indicator of water quality several times. I was hoping to use TDS as an indicator of when to do water changes, but it would likely take several weeks for my tank to reach levels over 100ppm.
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Trev nailed it pretty good. Torpedo beach is a fw substrate with no buffer capabilities to my knowledge.
Something else in the system is causing it to rise, do you have any rocks or shells in the system?
 
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