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post #1 of 15 (permalink) Old 03-21-2009, 11:57 PM Thread Starter
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water parameter question

i must admit that i do not totally understand water and its relationship with its individual properties. I know where ph, kh gh, nitrates, nitrite, ect need to be for certain fish.

I am having trouble with my PH in my 90 gal. i have 2 pieces of driftwood, pool filter sand as the substrate. I bought it at a pool place but it is actually red flint sand. the filter is an amiracle. I have added 50% tap water and 50% RO/DI. My Total hardness is 80 ppm, PH 8.6. The Nitrate is 10 and nitrite is 0. i tested my water out of the tap and it is 310 ppm total hardness and a ph of 8.1. Out of the RO/DI my total hardness is 1 ppm and ph of 6. I am not sure why the ph is staying up in the 8 area.

I would appreciate any insight into this mater.

Joel

Last edited by joestreich; 03-22-2009 at 02:38 AM.
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post #2 of 15 (permalink) Old 03-23-2009, 02:50 AM
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Starting with your tap water... Are you testing it fresh from the tap or after letting it sit for a day or more? To get a true pH it needs to sit, preferably with aeration. Fill a bucket, toss in an airstone and wait a day. If (from the tap) it is low in CO2 the pH will go down, if it is high in CO2 the pH will go up as it outgasses. When I do this I also add my dechlorinator since I would be anyways to use the water in a tank.

RO/DI water will have a neutral pH IF IT IS DEGASSED. Can't really be measured. If you use a test tube and drops you are really just measuring the pH after the drops are mixed in. If you use a normal pH meter you aren't going to get an acccurate reading either. However RO/DI water is eager to pick up gasses from the air, especially CO2. And the DI can even add CO2. So RO/DI water just sitting around will become weakly acidic, just by picking up CO2 from the air.

When you say total hardness do you mean you are measuring it with a TDS meter? Or are you using a gH test kit. Two very different things.

Have you checked the *sand* to see if it is inert? If a few drops of muriatic acid on it fizzes even a little you don't have an inert substrate and it might be a suspect in raising your pH.

Mixing your tap water which has the parameters you have descried with RO/DI water shouldn't give the parameters you are getting. So either there is something affecting the water chemistry which you are not taking into consideration, the test kits are giving inaccurate readings (are they old?) or maybe the tap water is worse than you thought. *Something* isn't adding up. Between the wood and fish waste the pH should be going down, not up, if your substrate and decorations are not affecting the water chemistry.

When cutting tap water with RO/DI some trial and error is needed. What you get really depends on the full composition of your tap water.
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post #3 of 15 (permalink) Old 03-23-2009, 12:14 PM Thread Starter
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Quote:
Originally Posted by bannh View Post
Starting with your tap water... Are you testing it fresh from the tap or after letting it sit for a day or more? To get a true pH it needs to sit, preferably with aeration. Fill a bucket, toss in an airstone and wait a day. If (from the tap) it is low in CO2 the pH will go down, if it is high in CO2 the pH will go up as it outgasses. When I do this I also add my dechlorinator since I would be anyways to use the water in a tank.
i was testing it fresh from the tap. i will take another reading after it sits and aerates for 24 hrs.


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RO/DI water will have a neutral pH IF IT IS DEGASSED. Can't really be measured. If you use a test tube and drops you are really just measuring the pH after the drops are mixed in. If you use a normal pH meter you aren't going to get an acccurate reading either. However RO/DI water is eager to pick up gasses from the air, especially CO2. And the DI can even add CO2. So RO/DI water just sitting around will become weakly acidic, just by picking up CO2 from the air.
I am using a PH meter not drops


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When you say total hardness do you mean you are measuring it with a TDS meter? Or are you using a gH test kit. Two very different things.
i am using a tds meter. the gh was about 3 and kh of 2 when using a test kits.


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Have you checked the *sand* to see if it is inert? If a few drops of muriatic acid on it fizzes even a little you don't have an inert substrate and it might be a suspect in raising your pH.
i have not checked the sand. Where would i get muriatic acid to perform this test?

Bannh, I appreciate the response. I have been frustrated with this for a couple weeks now. If it is the substrate then i will just find fish for this environment rather than fighting the water forever. Again thanks your post, it was very helpful. i will post my results after i test again. btw the ph was up to 9.2 this morning (using a PH meter)
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post #4 of 15 (permalink) Old 03-23-2009, 04:01 PM
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Unless your pH and TDS meters are badly in need of calibration, you have a big problem. But you already know that. It's very difficult to have a pH of 9.2 and a TDS of under 100 ppm.

As background, my tap water has a pH of 9.3 - 9.5, kH ~2 and a TDS of ~100 (I feel your pain). It's the result of soft acid water being treated with soda ash to dramatically raise the pH so it doesn't leach metals in old home plumbing and cause corrosion. If used, unbuffered, in a tank (and everything doesn't just die), the pH drops like a rock from the natural acids produced and lack of hardness and buffering.

Do you still have the test kits? If they are not too old you could always check using those, see if the result is anywhere near the readings you are getting with the meters. That's assuming you have the high range pH test drops. I would DEFINITELY check the kH in any case.

Muriatic acid is a VERY strong solution of hydrochloric acid. Used to clean masonary and also to adjust the pH in swimming pools. Don't know if they sell it in amounts less than a gallon but it's really not very expensive, I paid maybe $6/G. Know anyone with a pool? A single drop on concrete will fizz like crazy. Put a drop on glass (non-reactive) and nothing happens.

What you are having happen does NOT sound like a problem with your tap water supply (yet) but it never hurts to find out exactly what they are doing to it, how they are treating it, before supplying it to homes. I would imagine you get an annual water report (boring), there should also be a secondary contaminate report which is only slightly more interesting and available upon request. What you would want is to find someone who can tell you the actual treatment procedure. But again, doesn't sound like it's the real source of your problems, yet. Never hurts to check your tap water for gH/kH/TDS again, see if it has changed recently.

What kind of fish are you trying to keep? It's going to be tough to find many which can thrive at a pH over 9 and such a low TDS. Water like that just isn't stable. Do the fish show distress or are they dying?

What's up with your plants? Are they healthy or are they having problems?

And finally... *smiling* What do you WANT your water parameters to be? pH, gH, kH, TDS?
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post #5 of 15 (permalink) Old 03-23-2009, 04:22 PM Thread Starter
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hmm, where to begin.... i started this tank a couple of weeks ago. i bought it used and the filter(sump type) would be just moved from one place to another and i was going to add water ad my fish and go. the filter would already be established so no need to cycle. the problem came when i added play sand as substrate. i could not get it clean...i dont know how many times i stirred it up and it stayed cloudy for hours. i removed all the sand and add this red flint sand/rock. my goal was to keep my geophagus red head tapajos. i kept checking the water and the readings were not what i needed them to be.

i think the reason i have a high PH and low KH is that there are no fish in the tank and it is all ro/di water and something in that tank is driving up the PH (sand or rocks) i have removed all the larger rocks from the tank this morning. and will remove 50% of the water later and fill it back up again.

Originally, i wanted to keep my geophagus in there but after testing i think i might make it a tanganyika tank. the kh wouold be ok because i would go back to tap water which is like liquid rock.

i do have test kits and they are very new as are the meters. i will double check to make sure they are lining up.

i think ideally i would like my ph to be around 7 gh 4 and kh 3 approx. i didnt think this would be too hard to attain with a ro/di unit.

i will post again after doing some testing tonight.

-thanks for the response
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post #6 of 15 (permalink) Old 03-23-2009, 04:54 PM
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Even if you had crushed coral or aragonite substrate and all limestone rocks, when they slowly dissolved releasing carbonate, they would also release calcium, your gH/TDS would go up too. And it's not a very speedy process. In my rift lake tanks no matter how much calcium carbonate substrate & rocks I put in, I cannot hit a pH of 9 even with a light bioload of fish.

So no fish. But you have a sump which was fully biologically active. And maybe to keep the good bacteria happy and healthy until fish are added you have been putting in a little ammonia? (like fishless cycling) Ammonia is basic. Any chance you tested right after you added ammonia?
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post #7 of 15 (permalink) Old 03-24-2009, 02:03 AM Thread Starter
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unfortunatley no, i did not test after adding ammonia. i have not been adding ammonia or anything else. so now, i am sure my biological filtration has ceased to exist. i do have another sump in another tank so ican always grab some bio balls from over there to get thingsstarted again.

well now the problem has expanded to some degree. i used the ph meter to test my other tanks and they were also reading 9.2(all except my planted tank which reads at 7.5 CO2 injected). i decded to compare that with some newly aquired ph test(drops). the readings seemed to be about 1.0 off of what the meter was reading. do you have to calibrate new meters? i just received it in the mail and silly me, i thought it would have been calibrated.


The problem still remains however that for some reason my tanks are raising in PH right after going through the RO/Di unit. All the way up to 8.2 and still keeping a kh of 2. it just seems impossible to me.

i am going to fill a cup of ro/di and tap water tonight and take a reading and then see what it test at in the morning.
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post #8 of 15 (permalink) Old 03-24-2009, 02:54 AM
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No, you *shouldn't* have to calibrate a brand new meter. But who knows why it seems to be off. Calibration solution is cheap. Think on the bright side, it's probably not nearly as bad as you thought! I'd trust the drops more right now.

I kind of like puzzles like this (when it's not me), makes me think. I had gotten all the way to Biogenic Decalcification and was going to ask if there was any chance the tank was loaded with Vals, Hornwort and Anacharis and brightly lit.

There is a tiny little thought forming about how RO/DI water would be negatively affecting your mix but I need to think about it some more. Your idea of just mixing tap and RO/DI and letting it sit to test later, without ever being in a tank, is a good one. I'm curious.

Hey, and there is another good thing, it doesn't seem to be your sand or rocks either.

Oh, and don't count out ALL your good bacteria quite yet. Don't know how it's plumbed or if you can just recirculate through the sump and bypass the tank but I'll bet if you start dosing it with a little ammonia it still has a chance to bounce back. IME, it's more a lack of oxygen which first kills it off than a lack of *food*. Leave a closed canister filter sitting for a couple of weeks and it's just a foul anaerobic mess, much better chance with a sump.

Just one question this time. How do you mix the tap and RO/DI? I assume before you put it in the tank(s). No, I do not think it is being contaminated that way... just curious.
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post #9 of 15 (permalink) Old 03-24-2009, 03:11 AM Thread Starter
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thanks for taking interst in this bannh, i think you might be the only one.

just to clarify i did not mix the tap and ro/di tonight. i have them in seperate containers just to see what changes occur seperatly overnight. the tap tested at 8.6 PH(meter) and 7.5 (drops). tds was about 280. the ro/di tested 6.5 PH (meter) and 5.5 (drops). tds was 3.

you know it is kind of embarassing that i have not noticed this sooner. my ph test kits were always the 5.0-7.6 and it never occured to me that the ph could be higher....especially that much higher.

i will get some calibration solution and see what that does.

is there any way an old ro or di filter could be the cause of this? i am not sure how, but just a thought
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post #10 of 15 (permalink) Old 03-24-2009, 12:38 PM Thread Starter
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i just got done testing the tanks this morning and there was no change in the tap water. the RO/DI only changed a littler the PH was 6.5 and went to 7(meter)/ 5.5 went to 6 (drops) and the tds was 3 and now is 2. I am not sure what to make of this. i will check again when i get home tonight

I will stop and buy some PH calibration solution and calibrate the meter to see which one is accurate.

as far as water changes, you had asked how i was doing the mixing of the water outside the aquarium. i really wasnt. I would do several small water changes. Maybe 8-10%. I was then adding RO (not RO/DI) directly into the tanks. Everything was working fine(so i thought). i then got a 90 gal and i had to purchase a new test kit so i got the high PH test kit and found out that my PH was off the charts. Since then i have been trying everything to find out why the PH would be so high with RO and then RO/DI water. I must tell you that the unit is 2-3 years old and i have not changed a filter in it yet. I know that the charcoal filter and pre filters must be worthless but could the readings come out where they do at first and then change later based on old filters?
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post #11 of 15 (permalink) Old 03-24-2009, 03:40 PM
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The tiny thought I had forming yesterday was about which part of your RO/DI was failing. The membrane is still doing a lot so it came down to the resin. I'm actually glad to hear the filters haven't been changed. Saves a bunch of speculation on my part and questions to you. The sediment filter is dirt cheap, and the carbon block isn't much more. They need replacing. Although they do a lot of filtering themselves, they also do protect the RO membrane, equally important. Get a new DI cartridge too, they really should never be used to the point of full exhaustion (of either the anion OR cation resin), weird/bad ion exchange can start happening.

The membrane may still be fine, I would do the other stuff first and see what happens UNLESS you do not have a flush kit on it. Being able to flush the membrane makes a big difference IMO. If it's never been flushed it is covered in crud (scientific term). If you have money to burn, I'd just get a new one for the heck of it. You don't have to use it immediately and it will need to be replaced sooner or later.

I used to try to test the pH of RO/DI water until I figured out it was pretty pointless, too pure to get a real reading, drops or meter. But for the record, I consistently came up with a pH of 5.5 or so.

The pre-filters and RO membrane are pretty straightforward. Only stuff the about the size of, or smaller than water molecules can get through the membrane. The DI resin can get most of that.

Here's what took me a long time to *get*. DI resin doesn't absorb anything. It ONLY exchanges ions. Positive ions, called cations, and are EXCHANGED for hydrogen ions. Negatively charged ions, called anions are EXCHANGED for hydroxide ions. Maybe you knew this, I had heard the words but didn't fully comprehend it until I started recharging DI resin. If something has made it through the RO membrane but but does not have an ionic charge it's also going to go through the DI resin.

Short diversion: The reason you never want your anion or cation resin to get fully exhausted is because some ions have a stronger charger, are *stickier*, than others. Once the hydrogen or hydroxide ions are gone, you have no idea what kind of ions are replacing others. You can have a not-bad/very-sticky ion replace a very-bad/not-sticky ion which is then passed out of the resin. Once the cation OR anion resin is exhausted, you can actually be getting out worse water than goes in. This too I learned the hard way.

A TDS meter really only reads conductivity. Not everything is conductive. So even after your RO membrane and the DI resin, there can still be stuff in your water which you can't measure. Not much... but it isn't the same as distilled. You could put a little sugar in distilled water but it's not going to show up on a TDS meter, it's not conductive. So that Total Dissolved Solids isn't really all that *total*. Other more obvious things it won't detect is stuff like CO2. Then there is more confusing stuff like how not all ions are equally charged/conductive. And the water temperature affects readings too... If you get a reading of 200 ppm in very cold water then heat that water, the reading can go up. Some/most meters do have electronic compensation but it's not perfect.

Sorry I had to use so many words, but what I am try to say is even with all brand new filters, there can still be a tiny bit of stuff other than pure water after the RO/DI process, even if you have a 0 ppm reading on your TDS meter. With your old filters, especially the DI resin, who knows what is actually in that final RO/DI water.

I am still not clear how you are arriving at a consistent mix of tap and RO/DI if you are not mixing it before putting it in the tank. Have you considered a barrel? Fill'er up with whatever ratio you want, add Prime or something, drop in a water pump to circulate it and a heater to get it to the right temp, next day it's ready to go and very stable. Any tests or readings you do on it are going to be more accurate. If it's anywhere near the tanks you can put a piece of tubing on that pump you have been using to circulate the water and just pump it out to the tank(s). Try it, you'll love it!

If you cannot get the combo of pH, kH, gH and TDS which you really want/need just by changing the ration of tap and RO/DI water, you can adjust it in the barrel. Although my philosophy is to add as few potions and powders to the water as possible (excluding ferts) sometimes you may have to. Brewing it up in a barrel is a whole lot safer.

I think there is a bandaid solution which you could use immediately but there is no way you could do it unless you were premixing the water in a barrel. It's kind of unconventional (understatement) but I have tried it and it has worked, even for delicate fish and new fry. Don't really want to post it here because if done wrong it can go very badly.
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post #12 of 15 (permalink) Old 03-24-2009, 05:16 PM Thread Starter
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The tiny thought I had forming yesterday
Reading your response, i am glad it was a tiny thought otherwise i would still be reading it Seriously, thank you for taking your time and giving a detailed response.
i am ordering new filters and a membrane. i do have a flush system on it so i will try and flush that out tonight. i was thinking 10 minutes or so, what do you think? i may also remove the DI portion of the filter and se what my reading come out at.

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I am still not clear how you are arriving at a consistent mix of tap and RO/DI if you are not mixing it before putting it in the tank. Have you considered a barrel? Fill'er up with whatever ratio you want, add Prime or something, drop in a water pump to circulate it and a heater to get it to the right temp, next day it's ready to go and very stable. Any tests or readings you do on it are going to be more accurate. If it's anywhere near the tanks you can put a piece of tubing on that pump you have been using to circulate the water and just pump it out to the tank(s). Try it, you'll love it!
i am not sure either and maybe i wasnt getting the water parameters i thought i was. all my fish and plants seemed happy and spawned several times.... i was thinking about getting a barrel and doing just what you suggested. I know our sanitary district is selling plastic rain barrels for 25 bucks. (seems reasonable) i never thought my water was a problem until now i guess ignorence is bliss (purposefully misspelled for effect)

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I think there is a bandaid solution which you could use immediately but there is no way you could do it unless you were premixing the water in a barrel. It's kind of unconventional (understatement) but I have tried it and it has worked, even for delicate fish and new fry. Don't really want to post it here because if done wrong it can go very badly.

i am not looking for a bandaid solution, although you do have my curiosity peaked. if you dont mind, pm me and let me know what you would do for a tempory solution
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post #13 of 15 (permalink) Old 03-24-2009, 07:23 PM
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You won't regret the new filters and membrane.

Because of the age of your prefilters, the pressure to the membrane may be on the low side. I usually flush less time but 10 minutes sure won't hurt anything.

Right now I expect you WILL have better water straight from the RO and skipping the DI, even if the TDS is a higher. Very good choice IMO.

With happy fish and plants you don't have an urgent problem. But since you have the RO/DI housings and the pH and TDS meters, it's good to have everything in good working order so if you do want to do something specific you have the tools to do it.

There will always be debate over whether of not a *food grade* barrel is needed for water storage. I do not use a food grade barrel, others would say it is needed. Any time I add a new bucket or barrel I fill it with tap or waterchange water and let it sit, drain, refill, until the new plastic smell is gone. Best in the summer when you can leave it sitting in the sun. I haven't had a problem but would be negligent if I didn't mention it. A rain barrel for $25 is a great deal... I think my town wants $60.

I've sent you a PM, the way you are going to do it is much much better than the bandaid.
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post #14 of 15 (permalink) Old 03-25-2009, 12:13 AM Thread Starter
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So i ordered the filters, and am hoping that may have an effect on the water. I have also bought the calibration solution for my PH meter. i tested it in PH 7 and it was registering 8.1 i guess i am glad i checked it.

So right now my 90 gal (the one that we have been talking about) has a PH of 8 a KH of 5, GH of 3, and the TDS was at 83 ppm. Not sure what to think about this.

my ro/di water from last night went up to PH of 8.1 and TDS of 11 ppm

i will flush it tonight and bypass the di and see what happens tomorrow.
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post #15 of 15 (permalink) Old 04-07-2009, 11:03 PM Thread Starter
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Well, i changed all the filters in my ro/di unit. i emptied about 50% of the water and filled it back up. i let the filter run for a day and ran some test. my PH is at 7.9

i was really hoping that it would stay down but it seems that ina 24 hour period my ro water goes from about 6.5 to 7.9.

oh well, time to take a different approach.
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