Recently I purchased an RO/DI system capable of 100 gallons a day. Eventually I will be doing a 200 gallon SW tank, but for now my goal is to set up a 90 gallon discus tank. For those of you unfamiluar with Discus, they prefer a Ph near neutral with TDS readings very low. (picky fish)
Why do I need to use RO/DI water for this application? Well, my water out of the tap is liquid rock. Parameters are as follows:
Kh 220
GH 400 +
PH 8.2-8.4
TDS 420 PPM
As you can see trying to alter the PH with anything but an RO unit would be fruitless.
Now, out of the RO/DI my water tests as follows:
KH 0
GH 0
ph 6.0-6.2
TDS 0
What I would like to achieve (there is a little bit of flexability here)
KH ?
GH <50
Ph 6.8-7.4
TDS <60
I would like to stay away from phosphate buffers.
I was thinking I could get away with mixing a small amount of tap water with the RO/DI water (or I could just take water out after the membrame but before the DI). Would I be better off doing this or using a buffer? What KH should I shoot for, I anticipate 25% water changes daily.
Now, what I find intersting is that I have/had the 90 gallon tank full of tap water, with a few small koi (3-4") in the tank to get the cycle kick started.
I began to slowly replace some of the tank/tap water with RO/DI water in an attempt to slowly bring the water down in ph and TDS. I was doing this 5 gallons at a time as to not stress the fish too much (even though they are culls). I was actually shocked to see that initially, the PH shot up, not down. Is this unusual? Eventually the Ph does come down and I have dropped the TDS from 480 to 312 (this is over the course of two days with approximately 15 gallons swapped per day)
Am i going about this the wrong way or am I on the right track? if I am better off just using a buffer and replaceing all the water I would like to know. I ask this question on a reef forum as there seems to be alot more RODI knowledge here than on a freshwater forum.
Why do I need to use RO/DI water for this application? Well, my water out of the tap is liquid rock. Parameters are as follows:
Kh 220
GH 400 +
PH 8.2-8.4
TDS 420 PPM
As you can see trying to alter the PH with anything but an RO unit would be fruitless.
Now, out of the RO/DI my water tests as follows:
KH 0
GH 0
ph 6.0-6.2
TDS 0
What I would like to achieve (there is a little bit of flexability here)
KH ?
GH <50
Ph 6.8-7.4
TDS <60
I would like to stay away from phosphate buffers.
I was thinking I could get away with mixing a small amount of tap water with the RO/DI water (or I could just take water out after the membrame but before the DI). Would I be better off doing this or using a buffer? What KH should I shoot for, I anticipate 25% water changes daily.
Now, what I find intersting is that I have/had the 90 gallon tank full of tap water, with a few small koi (3-4") in the tank to get the cycle kick started.
I began to slowly replace some of the tank/tap water with RO/DI water in an attempt to slowly bring the water down in ph and TDS. I was doing this 5 gallons at a time as to not stress the fish too much (even though they are culls). I was actually shocked to see that initially, the PH shot up, not down. Is this unusual? Eventually the Ph does come down and I have dropped the TDS from 480 to 312 (this is over the course of two days with approximately 15 gallons swapped per day)
Am i going about this the wrong way or am I on the right track? if I am better off just using a buffer and replaceing all the water I would like to know. I ask this question on a reef forum as there seems to be alot more RODI knowledge here than on a freshwater forum.
