Temperature drop during waterchange

[seanbugeja]

Hi all, do you think a 2 degrees Celsius drop from 30C to 28C during a waterchange will negatively affect my fish? Just installed an ro unit and I'm thinking about how I should go about waterchange. Thanks guys

[Akili]

Hi all, do you think a 2 degrees Celsius drop from 30C to 28C during a waterchange will negatively affect my fish? Just installed an ro unit and I'm thinking about how I should go about waterchange. Thanks guysA 2 degree will not make any effect on your fish. Use 25 % RO 75% tap water mix gradually increase RO water with your water changes.

[seanbugeja]

yepp thats how i started 2 weeks ago...today i changed to 50% tap 50% ro...kh worrying me its at 4.5...otherwise all is great....

amonia 0
nitrite 0
nitrate 18
GH greater than 21
KH 4.5
ph 6.6 (was 7 when i used tap water)

[Akili]

Are your fish wild or a breeding pair? Your nitrate level are high.

[seanbugeja]

still young and i have 8 in a 230litre tank

[Jayy]

yepp thats how i started 2 weeks ago...today i changed to 50% tap 50% ro...kh worrying me its at 4.5...otherwise all is great....

amonia 0
nitrite 0
nitrate 18
GH greater than 21
KH 4.5
ph 6.6 (was 7 when i used tap water)

I'm curious about the 6.6 ph. a PH of 7 is neutral. Your RO system isnt capable of producing a PH lower than 7. So I wonder what is lowering it to 6.6? Have you cross-checked your PH readings with a different test? Maybe see if a lfs will test your water for you.

[seanbugeja]

will verify it tomorrow at my lfs...thanks jayy

[Akili]

still young and i have 8 in a 230litre tankYoung Discus do not need to be raised in RO water.Regular Tap water is fine.

[DJW]

I'm curious about the 6.6 ph. a PH of 7 is neutral. Your RO system isnt capable of producing a PH lower than 7. So I wonder what is lowering it to 6.6? Have you cross-checked your PH readings with a different test? Maybe see if a lfs will test your water for you.

The pH of RO water is typically between 5.2 and 6.8 because the RO membrane removes almost all of the KH and the water soaks up some CO2 from the atmosphere, forming carbonic acid. The reason that some people's RO has a higher pH than others is that if your water starts with a high KH the filter leaves a little bit of alkalinity.

If your source water has excess CO2 (typical of well water) the initial pH of the RO water will be very low until the water ages and the CO2 reaches equilibrium with the atmosphere. My RO settles at 6.7, the source water has KH=22. Its like half the bottle of test reagent.

KH of 4.5 is fine unless you plan to go a month before the next water change.:D

[seanbugeja]

thanks DJW...is it true what akili said? our tap water has general hardness off the charts a tds of 1400ppm. Many serious discus keepers here use ro water having such terrible water....otherwise parameters are fine and i have kept them in tap water for 8 months now...however some of my friends told me theyll be happier in ro..whats ur take? it would be much easier for me to keep my discus in tap water :)

[DJW]

thanks DJW...is it true what akili said? our tap water has general hardness off the charts a tds of 1400ppm. Many serious discus keepers here use ro water having such terrible water....otherwise parameters are fine and i have kept them in tap water for 8 months now...however some of my friends told me theyll be happier in ro..whats ur take? it would be much easier for me to keep my discus in tap water :)

A skinny person could walk on such water if they had a little faith.;)

I really don't know the answer. It is true that young discus are often raised successfully in very hard water. I would think that softening it with RO would be better. BTW, some of the water should be changed when the nitrates get to 10 ppm.

If your GH was 25 the general hardness would be 445 ppm, so I'm not sure if 1400 ppm is your GH or the TDS (total dissolved solids). 1400 ppm of general hardness would be a GH of 79!

[seanbugeja]

yepp my gh is off the chart...managed to get my tds down to 800 after 2 water changes with 25% ro and 1 waterchange (last saturday) with a 50% ro 50% tap mix...i acclimated them to it slowly. GH is still of the charts but slowly getting there. Our water in Malta is terrible!! water comes out of the tap with 25 nitrates..after calling the water company they said up to 50ppm is acceptable water source by law....thats when i switched to ro and from constantly having a 50ppm nitrates i managed to get it down to 18 which is an improvement...as it is going i might have to keep going down to 75% ro 25% tap.... we'll see :)

thanks for all your help DJW

[pitdogg2]

The pH of RO water is typically between 5.2 and 6.8 because the RO membrane removes almost all of the KH and the water soaks up some CO2 from the atmosphere, forming carbonic acid. The reason that some people's RO has a higher pH than others is that if your water starts with a high KH the filter leaves a little bit of alkalinity.


In all My RO use I have never found this to be the case. RO should have equal amounts of nothing so mine was always 7.0 BUT it takes very little to go either way, add a little acid and it can go to 5.0 add a little base and it could go to 8.0. So basically my 7.0 was a false reading of sorts so I'm a little surprised that you got a pH of 5.2 are you using an electronic pH pen? I do and have the regents to keep it precise as I can.

[DJW]

yepp my gh is off the chart...managed to get my tds down to 800 after 2 water changes with 25% ro and 1 waterchange (last saturday) with a 50% ro 50% tap mix...i acclimated them to it slowly. GH is still of the charts but slowly getting there. Our water in Malta is terrible!! water comes out of the tap with 25 nitrates..after calling the water company they said up to 50ppm is acceptable water source by law....thats when i switched to ro and from constantly having a 50ppm nitrates i managed to get it down to 18 which is an improvement...as it is going i might have to keep going down to 75% ro 25% tap.... we'll see :)

thanks for all your help DJW

The nitrates alone are a good reason to use RO in your case. Nitrates is why I use nothing but RO water. Is your water desalinated or is it ground water?

[DJW]

In all My RO use I have never found this to be the case. RO should have equal amounts of nothing so mine was always 7.0 BUT it takes very little to go either way, add a little acid and it can go to 5.0 add a little base and it could go to 8.0. So basically my 7.0 was a false reading of sorts so I'm a little surprised that you got a pH of 5.2 are you using an electronic pH pen? I do and have the regents to keep it precise as I can.

Water chemistry will give you a headache.

Pure water has a pH of 7.0 but that is only a theoretical value because as soon as pure water makes contact with the air it picks up CO2. Carbon dioxide is about 25 times as soluble in water as oxygen, so if you aerate the RO water it will contain around 2.5 ppm of CO2 at a tank temperature of 82F. If you google "pH of rain water" you will find explanations for this.

Another factor is that RO doesn't remove all impurities, it removes a percentage of the impurities that you start with in your source water. Its around 97% give or take depending on how well the membrane is working. When you measure 7 ppm of TDS in your product water, that is only a measure of conductivity being converted to an equivalent concentration of salt. Salt is a strong electrolyte. Weaker electrolytes like carbonate will not register as strongly, so you might measure 7 ppm of TDS and still have 10 ppm of carbonates, which is enough to raise the pH toward 7.0.

If you were to run your RO water through mixed-bed DI resin the TDS would go to 0 and the pH would be lower. You will go through a lot of resin doing this because the resin will get depleted more by CO2 than by the impurities you are trying to remove.

Glass bulb pH probes need a little bit of conductivity to function, and when you try to measure pH in nearly pure water they have a hard time finding the pH. You can put a tiny pinch of salt in the cup of RO and the meter will settle on a pH. I use one of these probes.

The pH of pure water can bounce up and down easily with the addition of small amounts of acid or base because there is nothing else in the water to chemically interfere with the ions.

Everybody's water is different, and even RO water varies from one place to another, unless it is further purified with DI.

[pitdogg2]

Water chemistry will give you a headache.

Pure water has a pH of 7.0 but that is only a theoretical value because as soon as pure water makes contact with the air it picks up CO2. Carbon dioxide is about 25 times as soluble in water as oxygen, so if you aerate the RO water it will contain around 2.5 ppm of CO2 at a tank temperature of 82F. If you google "pH of rain water" you will find explanations for this.

Another factor is that RO doesn't remove all impurities, it removes a percentage of the impurities that you start with in your source water. Its around 97% give or take depending on how well the membrane is working. When you measure 7 ppm of TDS in your product water, that is only a measure of conductivity being converted to an equivalent concentration of salt. Salt is a strong electrolyte. Weaker electrolytes like carbonate will not register as strongly, so you might measure 7 ppm of TDS and still have 10 ppm of carbonates, which is enough to raise the pH toward 7.0.

If you were to run your RO water through mixed-bed DI resin the TDS would go to 0 and the pH would be lower. You will go through a lot of resin doing this because the resin will get depleted more by CO2 than by the impurities you are trying to remove.

Glass bulb pH probes need a little bit of conductivity to function, and when you try to measure pH in nearly pure water they have a hard time finding the pH. You can put a tiny pinch of salt in the cup of RO and the meter will settle on a pH. I use one of these probes.

The pH of pure water can bounce up and down easily with the addition of small amounts of acid or base because there is nothing else in the water to chemically interfere with the ions.

Everybody's water is different, and even RO water varies from one place to another, unless it is further purified with DI.

Yes i completely understand mine was commercial RO/DI unit then was Irradiated post filter. I guess I just didn't think that it would fluctuate(pH) as much because end stage would still be very close either way ...live and learn EVERYDAY

[Len]

A skinny person could walk on such water if they had a little faith.;)

I really don't know the answer. It is true that young discus are often raised successfully in very hard water. I would think that softening it with RO would be better. BTW, some of the water should be changed when the nitrates get to 10 ppm.

If your GH was 25 the general hardness would be 445 ppm, so I'm not sure if 1400 ppm is your GH or the TDS (total dissolved solids). 1400 ppm of general hardness would be a GH of 79!

In order to get a more consistent idea of your water parameters, I would use ONE method of measuring and stick with it. Also be clear about what measure you are using. Trying to decipher what you have been posting leads me to believe you are using a test kit to measure gH and kH and also a TDS meter (hence the 1400 ppm). One does not directly translate to the other however so nobody could possible tell you that a gH of a given value would translate to a give TDS value. There are several reasons for this. One is the gH test kit is testing for calcium and magnesium whereas the value of Total Dissolved Solids is just that -- everything (calcium and magnesium included but only 2 factors). The second reason is that a meter will only approximate the actual value because all it is really doing is taking the conductivity of the water and multiplying it by a conversion factor depending on what it is calibrated with. Being conscientious of your water is a good thing and shows you want to provide what is best for your fish, but more important is giving them consistent clean water and practicing good husbandry and should be your starting point. From there, your fish will tell you if something is amiss so just watch them and see how they behave and how the display themselves. Chasing specific water parameters often leads to inconsistent water parameters and will only do more harm than good due to the stress it will cause the fish. It's simply not needed in most cases unless you are breeding wild fish and even sometimes then it isn't needed.

[CrazyAngels]

Are your fish wild or a breeding pair? Your nitrate level are high.

So many say Nitrate level is high, yet my tap water comes out at 20 ppm right out of faucet. So the key is to do yur water changes and keep it from going up any further.

[Jayy]

So many say Nitrate level is high, yet my tap water comes out at 20 ppm right out of faucet. So the key is to do yur water changes and keep it from going up any further.

Living with the conditions of your tap water is difficult when the tap water has 20 ppm nitrates.. But that's why an RO system is helpful in some cases. It would be better to use RO water to get the tap water nitrates down to 0 and then do water changes to keep it there. Or at least, lower than 10.

[DJW]

.. One does not directly translate to the other however so nobody could possible tell you that a gH of a given value would translate to a give TDS value..

General hardness is sometimes expressed as ppm of CaCO3 rather than degrees, and this is the conversion I was using... not to be confused with TDS. It was not clear whether the OP was using ppm of CaCO3 or TDS when he said 1400 ppm. In any case he's got extraordinarily hard water.

[Len]

My point was twofold 1) to pick a type of measurement and stick to it rather than mixing several, both for the OP's convenience as well as clarity for anyone reading. Carbonate hardness though is kH not gH (general hardness) which most test kits are really measuring calcium and magnesium. 2) to not focus so much on pinpoint numbers and chase them. The values posted in post 3 are perfectly fine in terms of hardness and don't need further fussing with.