buffering RO water question

[cellingson]

How are people out there buffering their RO water if at all? Do you mix some tap water in with the RO water, add a buffering compound such as bicarb, put some calciumcarbonate sand in the sump/substrate?
My TDS from my RO unit is 0. Which makes me concerned for easy fluctuation in pH since it is a planted tank with CO2. My tropical fish and plants are all doing fine, but I am looking to add a few discus and want to make sure everything will work for them.

[John_Nicholson]

Just add some tap water back nito your mix. Lots use either a 70/30 or 80/20 RO to tap.

-john

[DiscusJimmy]

I use Salifert - KH plus pH buffer. You don't have to use very much of it so it last a while and is quite cheap. I use 8g per 300 litres and that gives me KH of 2.5.

Have tried Seachem reef builder as well but it's expensive...

Personally, if I had a choice though I would do what John has suggested and do a RO / Tap mix. You will save a fortune!

[DonMD]

I have had excellent results with R/O Right, made by Kent. You can bring your TDS right up to where you want it.

I tried doing the RO / Tap mix, but my fish wouldn't breed in it. But for a planted tank, that would probably be best.

[Jnotjane]

I usually do 75/25 mix of RO/Tap. Always worked better for me than adding expensive buffers. This hobby is pricey enough without adding all the fancy water conditioners.

[limige]

don what are you doing to buffer the ph? RO RIGHT doesnt' contain any buffers and RO water is unstable by nature

[cellingson]

Doesn't it make sense to buffer the water with an additive? :confused: Mixing RO with tap water seems counterproductive. I purchased a nice RO unit to completely "purify" the tap water, but now I am going to add a little back. Maybe I should have bought a cheap RO unit that didn't completely purify the water and then just use straight up near RO water.

[DonMD]

don what are you doing to buffer the ph? RO RIGHT doesnt' contain any buffers and RO water is unstable by nature

I don't do anything to buffer the water. I don't even know what buffering the water means . . . But I can tell you that with the RO water with RO Right bringing up the TDS to about 85, I had zero problems with my parents. I've got over 100 fry from them at the moment. Once the fry were well attached, and swimming freely in the tank, I started using straight city water again, with a TDS of about 285. Never thought I had to buffer.

[John_Nicholson]

Doesn't it make sense to buffer the water with an additive? :confused: Mixing RO with tap water seems counterproductive. I purchased a nice RO unit to completely "purify" the tap water, but now I am going to add a little back. Maybe I should have bought a cheap RO unit that didn't completely purify the water and then just use straight up near RO water.

Depends on if you want to throw money away or not. In 99% of the cases adding tap works just fine and is a lot cheaper.

-john

[limige]

Don buffer refers to the waters ability to resist change. Straight RO water is extremely unstable and will easily swing ph. Add a buffer like baking soda to raise the ph. If you run your test kits it reads as the KH value. Acids can buffer if you want to drop the ph. My issue is I want to to maintain a low ph but add some buffering so the ph doesnt crash on me.
As long as your doing daily water changes you probably wont have to worry about much but over a few days ph can take a dive. My RO Right has been dropping in the 5's after a few days.

Adding just 1/2 gallon of well water brings my ph up to almost 7. Still very low KH. Im still looking for the answer to stabilize the tank better.

If you read the RO Right canister they clearly state it has no buffers added. So be warned your ph could be swinging and you dont even realize it

[cellingson]

Don, a buffering agent can bind to hydrogen ions preventing acidosis, or release hydrogen ions to prevent alkalosis. HCO3 is a classic example. It both gives and receives hydrogen ions. Ultimately allowing for more swings in hydrogen ion concentration before changes in pH.

Thanks for the responses. I'll just add some tap water back to the RO water.

Limige sounds like you just add a small volume of well water, 1/2 gallon of well water : ? RO water

[DonMD]

You guys are all reminding me of why I failed chemistry in high school ~ sigh ~

[limige]

I am mixing 30 gallons of RO to 1/2 of well. I had very poor hatch rates with 3 gallons of well added so i'm reluctant to put any more than I have to. I would much rather find something I can add to stabilize it solid at 6.5-7 PH and have a solid KH.

after mixing the RO Right my ph is at 6 and unstable. I haven't checked it but the RO/DI should be neutral at 7 correct? so the RO right must be dropping it. I am worried if I add an acid it will lower it further. is there an acidic buffer I can add to stabilize it at 6-7?
my well is very high in calcium, its natural ph is 8.3. so its got a nasty bounce when I mix it. still trying to resolve this issue

[Len]

Don buffer refers to the waters ability to resist change. Straight RO water is extremely unstable and will easily swing ph. Add a buffer like baking soda to raise the ph. If you run your test kits it reads as the KH value. Acids can buffer if you want to drop the ph. My issue is I want to to maintain a low ph but add some buffering so the ph doesnt crash on me.
As long as your doing daily water changes you probably wont have to worry about much but over a few days ph can take a dive. My RO Right has been dropping in the 5's after a few days.

Adding just 1/2 gallon of well water brings my ph up to almost 7. Still very low KH. Im still looking for the answer to stabilize the tank better.

If you read the RO Right canister they clearly state it has no buffers added. So be warned your ph could be swinging and you dont even realize it



Just a word of caution, using baking soda isn't a great way to adjust your pH. pH will raise temporarily, but can just as easily fall quickly, so it's far from stabilizing.

[limige]

ok I haven't tried it but seems I've read some ppl do this

[Len]

They do, but it isn't very effective in terms of stability. Unless you have a specific reason, I wouldn't target a particular number because you'll be forever chasing it. Let your pH fall where it may and maintain good water quality instead. Also keep im mind that just because your pH went to 6 after it went through an RO unit doesn't mean it isn't stable, it just has a lower carbonate hardness and a corresponding lower pH.

[DiscusJimmy]

After the water exits the RO unit it should have no KH or GH. If you want to add buffering you will need to increase the KH (carbonate hardness). The carbonate within the water acts as a "cushion" to absorb acid produced by the bacteria, fish, plants and any decaying waste. Once this is used up the acid levels will rise and cause the pH to fall...which can be quite rapid

You can get lots of products to increased the KH, but the trade off is that they will all increase the pH. Most people recommend a KH of 3 to keep the water stable. However if you do regular water changes you can have it lower.

Also if your using a liquid test kit, you can add double the amount of water to be tested to get a more accurate KH...well to the nearest .5 anyway

[Second Hand Pat]

After the water exits the RO unit it should have no KH or GH. If you want to add buffering you will need to increase the KH (carbonate hardness). The carbonate within the water acts as a "cushion" to absorb acid produced by the bacteria, fish, plants and any decaying waste. Once this is used up the acid levels will rise and cause the pH to fall...which can be quite rapid

You can get lots of products to increased the KH, but the trade off is that they will all increase the pH. Most people recommend a KH of 3 to keep the water stable. However if you do regular water changes you can have it lower.

Also if your using a liquid test kit, you can add double the amount of water to be tested to get a more accurate KH...well to the nearest .5 anyway

If using a RO unit without the DI there can be remaining minerals etc in the water and this is illustrated with having a measurable TDS. When you add the DI part the TDS should be zero.

[limige]

ok, well I need to add something because my ph is fluctuating too much. I can't add much well water because the high calcium wont' let eggs hatch. so I need to buy something to use that won't affect hatching too much

[cellingson]

They do, but it isn't very effective in terms of stability. Unless you have a specific reason, I wouldn't target a particular number because you'll be forever chasing it. Let your pH fall where it may and maintain good water quality instead. Also keep im mind that just because your pH went to 6 after it went through an RO unit doesn't mean it isn't stable, it just has a lower carbonate hardness and a corresponding lower pH.

Hmm…I have read about bicarb use in the reef word. And that is their suggestion to raise pH, and based on my chemistry experience it is suppose to buffer pH though it certainly will raise pH. The human body uses bicarb and a few proteins to buffer the pH of blood. But is also has lungs and kidneys that regulate the amount of bicarb.

I am thinking out loud here, so just an idea. If you do an internet search you can find some buffers that may be suitable for aquariums. Monopotassium phosphate may work, but would increased phosphate levels and potential algae blooms. The green leaf aquarium sells it as a macronutrient for plants. You also could consider calcium carbonate. I know you have been trying to get this out of your water. Something I have considered is adding a handful of coral sand-which I believe is high in calcium carbonate. As the pH drops the calcium carbonate should leach out and buffer the acidosis. Your pH would slowly become more alkaline with a prolonged time, but with daily water changes this should not be a factor. You could always test any thing you try in a bucket of water. To test the buffering abilities you could add an acid and see how much it takes to cause a rapid fall in pH.

[Len]

ok, well I need to add something because my ph is fluctuating too much. I can't add much well water because the high calcium wont' let eggs hatch. so I need to buy something to use that won't affect hatching too much

You would only have to add a small amount back. I'm still curious as to why you say it fluctuates to much though. Is it because of the initial drop to 6 or have you noticed something else?

[limige]

after I age it for a day, do a water change then wait two days before the next water change the ph begins to drop. it's dropping about .5 in that time period. god forbid If I ever tried a week between wc's. I'm talking about going from 6.2 to 5.7. you start dropping that low you loose your bacteria in the filter and food sours quickly if not eaten. I'm by myself with nobody to help watch the tanks.

[Len]

lol, nope. That's an old wive's tale. I've had pH in the 4s and the bio filtration still works fine. I certainly wouldn't let it go that low all at once or I'd imagine the bacteria would die off. If you're really concerned about it, just add back some of your reject water, but I honestly think you're too focused on your pH. a .5 drop in a day is nothing to worry about. My water from the tap is about 50 ppm TDS and the carbonate hardness isn't measurable by a test kit, but my fish are fine and have spawned in it many times so they must be happy :)

[limige]

ok, Im just worried the fluctuations would stress them over time. if it drops to 5.7 then I refill the tank with 6.2 that's a sharp rise. the drop is over days, its stable for a day then it tapers down. not sure if it would settle out or not.

for now i'm mixed some well water back in. going to see how that works over the next few weeks. I was mostly concerned about the fry I have going. they are just over a week old and I don't want to do anything to loose them. its a decent spawn of about 60

[Len]

Well, keep us posted and good luck with the fry. Throw some pictures up if you have the opportunity.

[limige]

day 8 yesterday

[oliverk]

Just add some tap water back nito your mix. Lots use either a 70/30 or 80/20 RO to tap.

-john

Hey at one point you suggested to use the RO reject back in the system - the thought being that the chlorine/chloramine has been broken by the carbon prefilter and that any resulting ammonia is a) also removed before rejection or is of the non harmful kind. I kept this suggestion in reserve for a while but finally bought an Ammonia Alert which measures only harmful ammonia (thinking about buying a liquid test as well) and ........

I finally took the hint and to date have not had any ill affects or effects. Been wanting to thank you for the suggestion, but will note that most of my RO reject is going to plants not into the tank..... I remembered that RO rejects something like 3 bad for 1 good so........ I'm sure I'm not even using 1/3 of the RO reject but only a little here and there. (I do extract some RO good for drinking) otherwise it would be a simple marriage of the original tap (absent the chlorine chloramine and ammonia) that many use after treatment with no ill affects or effects. This said I have not been doing breeding - though have had two batches of eggs laid, nor dealing with fry but been growing out juvies)

Thanks for the tip - has made my life easier.

(Note my RO filter is not rated at 100% removal on everything and I think the same is true for most DI filtrations - they get most of it (usually 85% +) but depending on your source water and sensitivity of your tests .....)

[cellingson]

limige, I found this thread, maybe you will find it helpful.
http://forum.simplydiscus.com/showthread.php?103814-DIY-Remineralization-for-RO-Water

[limige]

thanks, informative thread.

one thing i'm gathering is the my enemy (calcium) is the main thing that stabilizes PH. darn it...
i'm going to get playing with the amount of well water I add and see what happens

[cellingson]

Would be the cheaper way to go. I decided to just buy the compounds at the greenleefaquarium.com and put them back in. Then I know exactly what is going in my water. I'll let you know how it is working. Nice looking fry. If you decided to ship and sell let me know.

Saw you were working in a Camaro in the Career thread, did you finish it?

[limige]

Wow that was way back. Not totally no. Needed an exhaust a new throttle body and dyno tune. But someone decided to back into it and I really didnt have the money or the ambition. I moved to a small town and the cops would poke around every time I drove it. I sold it and mived on. Do more fishing and hunting since I left the city.