Tds good are bad

[MadMatt]

How often do you do water changes? And how much do you change 50%??? 25%???

Ok my tap water ph is 7.5 with a API kit, the tap water tds is 345 and the TDS on the RO water is 8 with a HM Digital TDS METER 3 and the ph of the ro water alone is 5.0 with api kit. At the moment the ph in the tank is about 8 and the discus r not swimming as usual they r at the bottom of the tank most of the time. I had full tap water in the tank and they lay and I got some wigglers but doing water change they all become white. then I did a water change and take about half of the water out then replace it with half tap and half ro and the fish become less active, but if I change it back to full tap they will start swim as normal

[dj200]

I do water change every day and I change about 25%

[nc0gnet0]

when I do a water change, at the moment they lay about a week ago and I did a water change and take out about half of the water then mix ro and tap water and add it back and they just on 1 corner.

Wish I had seen this earlier..........

Ok, for starters, I highly doubt that what you are seeing is the result of a PH crash. You only did a 50 % water change, and you added back an Ro/Tap mix. Something else is going on here, so forget everything you have read up to this point. And for starters, just be aware that a PH test of RO water with virtually no pH is very inaccurate. By definition of the term, distilled water has no pH.

So, with this in mind, let's see what else is going on here. Is this a brand new RO unit? Did you flush it really well before using water that came out of it? You should run them a good 4-6 hours and dump out the first batch of water. Only after that should you begin to use the water.

For future reference, if one were to start with 30 gallons of relatively high pH water, lets say 300 tds and a pH of 8.0, do a 50% water change with PURE RO water, in all likely hood, while the buffering capacity of the water will have been reduced (TDS would now be 150), There will be little to NO change in the PH. The RO unit is not adding anything to the water that would effect pH, only removing the minerals that make up the buffering content of the water (mainly calcium and magnesium). Not until you get into the lower ranges of the TDS values (sub 80 tds) will you start to see any possible change in pH.


-Rick

[MadMatt]

+1
Mr.Nc0gnet0 has helped me before and you can take his advise to the bank.

I agree, after reading this thread and seeing where its all going there is more then just a ph thing here, and the crash or dip in ph is not the real issue but simply a symptom.
My RO water has never effected the parameters of my tap water in anyway besides reducing the TDS.
So I have to strongly agree with Mr.nc0gnet0.
I guess the next thing we should know is how much of a ph swing happens when this person ages their tap water.

Wish I had seen this earlier..........

Ok, for starters, I highly doubt that what you are seeing is the result of a PH crash. You only did a 50 % water change, and you added back an Ro/Tap mix. Something else is going on here, so forget everything you have read up to this point. And for starters, just be aware that a PH test of RO water with virtually no pH is very inaccurate. By definition of the term, distilled water has no pH.

So, with this in mind, let's see what else is going on here. Is this a brand new RO unit? Did you flush it really well before using water that came out of it? You should run them a good 4-6 hours and dump out the first batch of water. Only after that should you begin to use the water.

For future reference, if one were to start with 30 gallons of relatively high pH water, lets say 300 tds and a pH of 8.0, do a 50% water change with PURE RO water, in all likely hood, while the buffering capacity of the water will have been reduced (TDS would now be 150), There will be little to NO change in the PH. The RO unit is not adding anything to the water that would effect pH, only removing the minerals that make up the buffering content of the water (mainly calcium and magnesium). Not until you get into the lower ranges of the TDS values (sub 80 tds) will you start to see any possible change in pH.


-Rick

[nc0gnet0]

+1
Mr.Nc0gnet0 has helped me before and you can take his advise to the bank.

I agree, after reading this thread and seeing where its all going there is more then just a ph thing here, and the crash or dip in ph is not the real issue but simply a symptom.
My RO water has never effected the parameters of my tap water in anyway besides reducing the TDS.
So I have to strongly agree with Mr.nc0gnet0.
I guess the next thing we should know is how much of a ph swing happens when this person ages their tap water.

Nothing that the Op has said states that there was any pH crash. It is only speculation by those that replied that was the case. If you read further we know this:

pH of OP tap water out of tap.......7.5
pH of OP water in tank right now........8.0
pH of ro/tap water mix............(6.0 disregard this)

As you can see, there was no pH crash when the OP did a 50% water change with an RO/tap water mix of 50%-otherwise they tank would not be currently at 8.0 pH.
We do know that the Op appears to have some C02 in his tap (hence the increase in pH from the tap water measurement and the tank measurement.


I would like to know what the ratio of Ro to tap mix the Op is using, Also, Op needs to age the tap water prior to mixing it with the Tap water.

I would also like to clarify that OP had a tank for of tap, then did a 50% water change using an RO/tap mix. This is my understanding.

[dj200]

I got this ro system about 1 year ago, but the tds from the ro unit is 8 to 10. Change back the tank to full tap water now and the fish are swimming fine. The ph in the tank now about 7.6. I did 2 water change with only tap water and they r not at the bottom of the tank any more.

[nc0gnet0]

I got this ro system about 1 year ago, but the tds from the ro unit is 8 to 10. Change back the tank to full tap water now and the fish are swimming fine. The ph in the tank now about 7.6. I did 2 water change with only tap water and they r not at the bottom of the tank any more.

That's great news, but you didn't answer any of my questions.

Has the RO unit been in use for the entire year, or did you just recently begin using it again?

[dj200]

It has not been use for about 6 to 9 month just start using it back from about march

[nc0gnet0]

It has not been use for about 6 to 9 month just start using it back from about march

I would like to know what the ratio of Ro to tap mix the Op is using, Also, Op needs to age the tap water prior to mixing it with the Tap water.

I would also like to clarify that OP had a tank full of tap, then did a 50% water change using an RO/tap mix. This is my understanding.

[dj200]

50:50

[dj200]

when I did my water change I change 50% of the water and use tap water, then if I am going to use ro I would do a 50% water and mix the 50%ro to 50% tap water and put it back in the tank