Ph swing issues in co2 planted tank - The Planted Tank Forum
 
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post #1 of 12 (permalink) Old 10-16-2012, 05:39 PM Thread Starter
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Ph swing issues in co2 planted tank

I need some experience on ph swings in my planted tank. I started switching over to almost complete r/o H20 because of super high GH & Kh calcium carbonate issues with my tap. I make my own gh booster trying to recreate seachem equilibrium. 2 parts ca, 1 part mg. 2 parts potassium sulfate. I just add enough to increase my gh to 4gh for now. I add only enough baking soda for kh of 3 or 4 as well. This creates a ph of 6.6. I thought this would get rid of my early morning ph swing in the mid 7s. I would like a more stable ph , even though I realize without a ph controller there will be swings. I have had tanks in other distributions that were more stable. The plants should produce enough co2 at night without air stones to lower ph, mine rises!!! I run 3 bubbles a second & after 10pm the fish show signs of stress so I installed a shut off valve on a timer. So it does not run at night. I have a small amount of surface agitation just enough to create a slight ripple.
The tank build: 10 gal
30 watts old school t8 wide spectrum (2x15)
pressurized: co2 3-4 bubbles a second sent into power head
substrate: flourite & slight covering of supernatural sand
filter: small external canister & internal sponge powerhead
plants: fast growing stems microsrium, pearl grass, anibius

The co2 is sent into the bottom sponge an sent through the ventura which grinds up very tiny bubbles which are sent around the tank. While it runs the ph is stable & drops but when its off my ph rises. I do have a rock in the tank & checked it for limestine & it passed. Also the tank is only 6 weeks old & I know the tank is not fully cycled yet. First stage is solid second stage is week. I only have 1 small tetra so I was wondering if this was the problem. I did pick up a nitrite spike but do to other issues I did water changes & think I have stalled the cycle.The plants are growing well but no pearling. Any ideas on what's going, why does my ph rise??? Thanks
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post #2 of 12 (permalink) Old 10-17-2012, 12:14 AM
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It seems that Baking soda and Co2 fight against each other and the GH (I use Seachem Equilibrium) acts as a buffer. I add slight amounts of carbonate to my water and the pH will rise over 7 from 6.4 if i am not careful. Right now my pH is 6.2 and my kH is 1. My plants/ fish look very good.
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post #3 of 12 (permalink) Old 10-17-2012, 12:37 AM
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huh? the pH is suppose to rise back up when the CO2 is off. Am I missing something?


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post #4 of 12 (permalink) Old 10-17-2012, 12:48 AM
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You may have added too much baking soda
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post #5 of 12 (permalink) Old 10-17-2012, 03:15 AM
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almost complete r/o H20
gh booster to 4gh for now.
baking soda for kh of 3 or 4
ph of 6.6. How soon after mixing do you measure the pH? Try mixing some and testing after several hours or overnight.

early morning ph swing in the mid 7s. You mean before the lights come (or very soon sfter) on pH is in the 7s?
I would like a more stable ph Why? The fish do not care.
The plants should produce enough co2 at night without air stones to lower ph, mine rises!!! If you DOSE CO2 during the day you are dosing more than the plants are producing at night. So you turn off the dosing, and the plants and fish are the only significant sources, and they are not producing as much CO2.

I run 3 bubbles a second & after 10pm the fish show signs of stress. Yes, with dosing, plants and fish all producing CO2 it can get to be a bit much.
so I installed a shut off valve on a timer. So it does not run at night. I have a small amount of surface agitation just enough to create a slight ripple. Good.

The tank build: 10 gal
30 watts old school t8 wide spectrum (2x15)
pressurized: co2 3-4 bubbles a second sent into power head
substrate: flourite & slight covering of supernatural sand
filter: small external canister & internal sponge powerhead
plants: fast growing stems, microsorium, pearl grass, anubius

The co2 is sent into the bottom sponge an sent through the venturi which grinds up very tiny bubbles which are sent around the tank. While it runs the ph is stable & drops Typical but when its off my ph rises. Also typical. I do have a rock in the tank & checked it for limestone & it passed.

Also the tank is only 6 weeks old & I know the tank is not fully cycled yet. First stage is solid second stage is week. I only have 1 small tetra so I was wondering if this was the problem. I did pick up a nitrite spike but do to other issues I did water changes & think I have stalled the cycle.
Nitrifying bacteria grow best when the pH is on the alkaline side of neutral. They need some carbonates. I do not know if it is actually the low pH, or the low carbonates that slows them down. To cycle this tank I would add Nitrospira species of bacteria from a bottle, or else grow your own bacteria in water conditions more conducive to their growth. Look for any of my posts about the fishless cycle. Do not cycle with fish.

The plants are growing well but no pearling.
Pearling is a measure comparing the amount of oxygen the plants are producing compared to the amount of oxygen immediately surrounding the leaf.
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post #6 of 12 (permalink) Old 10-17-2012, 07:31 AM Thread Starter
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Thanks for all of your input. I guess each tank & water distribution is different even r/o usage. I guess I am expecting what my old tank was doing, which was on a good day the ph would actually rise during the day with lights because my diffuser was not always working the same way every day. My ph would not rise above 7.0 until late during the light period because it could not keep up with my plants demands even on a good day. Amano even talks about this. The point is at night my ph fell because my plants were doing very well and we all know co2 is produced at night. To me, I would think that ph would fall at night in a healthy aquarium because of co2 respiration. The only way to keep it down during the illumination period would be with the addition of correct amounts of co2. Of course this pertains mostly to softer water which is more acid anyway. The water I am making has a lower ph & I am not using air stones which will drive the ph up. Another possible problem I was thinking that maybe even a little to much surface agitation could out gas co2 & drive it up. Also since the tank is not cycled could nitrites cause a higher ph????? To answer MisterGreen: I have had healthy tanks where the ph stayed down all night into the morning with plenty of o2 all day & night with no buffer at all with fish that showed no signs of stress.
Finally to answer Diana, Yes I measured my ph after making my gh & kh adjustments a long with seachems fish trace elements. Ph 6.5- 6.8 ish. I will take your advice an see if it stays that way over a day or so, I have not done that yet.
Diana I followed your thread on fishless cycling I am currently in the middle of that for my quarantine tank. Its a monster, Im not sure if 5 ppms is a good start but thats what I did & IN LESS THAN A WEEK Im off the chart in nitrites & nitrates . I am having trouble in calculating the ammonia because the bio demand is so large. Doing lot's of water changes, & trying not to let NH3 go to zero. I will never cycle a tank again without doing fishless, its the only way to go. Thanks again & if anybody could answer my question on nitrites causing ph rises or could a planted tank that has not cycled yet cause higher ph's. Thanks
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post #7 of 12 (permalink) Old 10-19-2012, 04:39 AM
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Fishless cycle:
The bacteria will do the best with these conditions:
KH over 3 German degrees of hardness. They need the carbon from the carbonate.
pH in the alkaline side of neutral. I am not sure if this is just another way of making sure there are enough carbonates, or because some reaction the bacteria depend on happens better in alkaline surroundings.
Ammonia and nitrite under 5 ppm. These are toxic to the bacteria in higher levels.
Nitrate: They do not care. If you are already getting high nitrate perhaps the bacteria are already growing well, or maybe there is another source.

I do not think the nitrite controls the pH, but I think adding ammonia makes the water more alkaline. At least, when I started doing the fishless cycle and overdosed the ammonia the pH went up.
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post #8 of 12 (permalink) Old 10-19-2012, 07:07 AM Thread Starter
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Smile

I agree I have noticed a higher ph with the addition of ammonia. I am struggling to pick up where I am with the nitrites. They are off the scale. I keep doing 50% water changes thinking I will keep up and my reward is even higher nitrites!!!! 5ppm but I am sure they are higher. I think the problem was when I started adding ammonia I cut in some tape water with r/o water & dosed prime to make sure all chlorine was gone. I get strange readings that usually measure ammonia lower than it really is. I could have triple dosed. I find the nitrites read closer to real world, but I am concerned about using any more prime because I do not trust the readings. That's why I am using pure r/o water with my gh booster & I also add phosphates as well. I will take your advice on the kh. I think I am running closer to 2kh, maybe I will try to boost it to see if it helps. I am concerned that my nitrites are to high. Therefore, I will be chasing my tail. Its not like using straight tap where I can do 90% water changes, I am more around 40 50% daily with the r/o. I add just enough to bring ammonia to .5ppm. I have watched it go to zero before I re spike the tank.
On a side note I believe my other planted tank cycled finally tonight. Nitrites went from .5pp this afternoon to zero!!
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post #9 of 12 (permalink) Old 10-19-2012, 03:39 PM
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Household ammonia has a pH of 12 so it definitely it will definitely raise your pH.

Good luck, and grats on getting the nitrites to zero in the first tank. Sometimes the amount of patience it takes is difficult.
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post #10 of 12 (permalink) Old 10-20-2012, 12:17 AM
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What I would do: (Exactly what I did a month or so ago!)

100% + water change. Dig into the substrate a bit to drain out that last little bit.
Then a little bit of refill and drain it again. (Rinsing the tank decor of any lingering nitrogen.)
Clean the filters. (gently rinse and reuse the media)

Then refill the tank with just ONE dose of dechlor. Do not overdose.
Check the KH, and maintain at least 3 German degrees of hardness.
Then add BARELY enough ammonia to bring it to 3 ppm, no higher, and 2 ppm is better than going too high.

Let that run for 24 hours and test the nitrite and ammonia, and KH.

If the nitrite is over 5 ppm then skip dosing the ammonia. You will not starve the bacteria by making them wait a day to be fed.
If the ammonia is low, and the nitrites are low, then dose the ammonia to BARELY reach 3 ppm.
If the KH is dropping add baking soda.

Next day, test again. Ammonia and nitrite. Continue dosing just a little ammonia, never too much, until the nitrite removing bacteria catch up. Might take a week.
Then add a little more ammonia to really reach 3 ppm.

When you can add enough ammonia to reach 3 ppm and the bacteria remove it all overnight (24 hours), and the nitrites are zero, the cycle is complete.
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post #11 of 12 (permalink) Old 10-20-2012, 04:57 AM Thread Starter
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Diana, this is all glass no substrate quarantine tank. I started it after the planted tank I just cycled. I know backwards. I really needed a quarantine tank anyway like all of us. If I do a 100% water change with 2 internal tiny canisters I will fry the bacteria. I have been cutting down on the ammonia but according to what you say now its ok to let them go to zero for a while, but you stated on prior posts not to let them go to zero. I worked hard to get this far I would hate to kill them. I have already had several zero readings just to re spike & they were able to recover in a few hours. I agree a big water change is inline, but to use prime or another conditioner that will yield false readings scares me. The thing I like about r/o water is it clears the way for accurate readings provided nutrients & temp are in order. The thing I do not like about r/o water is the waste. I increased my kh like you said. I think regular water changes are inline + a reduction in ammonia, if I can get over my paranoia of running out of ammonia. Like you said reduce ammonia, I have been trying to hold .5- 1ppm, even at this level 50% change yields off scale in nitrites. Would adding gravel assist in my situation??? Probably should be my next move. Sorry I was not more specific on this tank. I think I answered my own question. Agreed, the tank needs substrate to speed things up? I have been watching too many Discus breeders & all the glass tanks. I thought I could pull this off,but gravel will beef up surface area. Thanks for all the input. Let me know what you think, thanks.
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post #12 of 12 (permalink) Old 10-21-2012, 06:44 PM Thread Starter
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Holding tank almost finished cycled

Well I thought it would have taken longer. I cut back on the water changes & added substrate. Last night finally the nitrite came down to readable levels & the ammonia level falls from 2ppm to zero in about 5 hours. It should cycle up in the next day or 2 at this rate. Fishless cycling, the only way to go. 10 gallon almost fully cycled in 2.5 weeks. Does anybody have suggestions for ph control in this tank since it is not a planted tank , one that does not destroy the bio system or does something funny to the food for the bacteria? Does seachem make something? Is their ph buffer safe for the bio system?? Thanks
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