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RafflesGold Forums > Discussion Area > Green Water, Filtration and Tank Setup
nzkingyo
Hi I have been keeping goldfish for about 10 years and breeding them seriously for the last 5. I have a question regarding green water and high pH, I have looked through the archives and can't seem to find anything hence this post.
My query is I have started 2 new 1200 L ponds and seeded them with green water and while the amonia, nitrite and nitrate are fantastic at 0 (I have 6 medium sized fish in each pond) the pH is out of what I would normally class as an acceptable range at between 9 and 9.5. I have tried changing about 50% of the water yesterday and it dropped to 8.9 but this evening it was back up to 9.4, is this high pH normal? Is it part of the initialisation period or have I done something seriously wrong?
A third pond (same size and fish loading) that I started a week and a half ago is currently sitting at 7.6 and is slowly becoming more green. In the last 24 hours it has gone from pretty clear to having a tinge of green and I'm worried that the pH on that one will also climb into the realms of the unacceptable.
I want to learn how to use green water effectively as I beleive the results I've seen posted and the fact that most fish farms and breeders tend to use it would suggest that to master it will be worth the effort.
Also the ponds I run on BB tend to be great in terms of amonia and nitrate but I always struggle to control the nitrates.
CP
Nothing wrong, perfectly normal.
pH for greenwater can go as high as 10.
bekko
The algae removes carbon dioxide (a weak acid) for photosynthesis. As the CO2 is depleted the pH rises. At night, when photosynthesis is shut down, CO2 is replenished through respiration. At dawn, your pH should be about the same as clear water. Somehow, these fluctuations do not bother the fish.

-steve
nzkingyo
Thanks guys, makes me feel so much better. I'll check the pH tomorrow morning and let you know what it reads. Glad to know my fish will be happy in there lovely green environment.
nzkingyo
Checked pH this morning and it is still 9.3, newer pond pH has now risen to 8.2, any thoughts???
bekko
Do you have exposed concrete?

-steve
nzkingyo
Hi Bekko, no concrete my ponds are lined with pond liner 500um thick. I have been using the same material for 8 years but have only recently seriously tried to run green water ponds. Prior to this attempt I have run clean water with UV and bio mechanical filtration using BB. The previous ponds have had no problem with pH only with nitrates which is why I'm trying to go "green".
bekko
Are you using bubble aeration?

-steve
Kinder
Hi nzkingyo,

Its quiet normal high pH with greenwater. Do you buffer your water, buffering with baking powder will keep the water in-check...around pH 8.4 mark. So that way you should not get any fluctuation ...only problem cost...since you have a large setup.

kinder
nzkingyo
HI Bekko, no not using any aeration, was wondering bout that as some of the post I've read reccommend it for night when the algae are using the oxygen as no photosynthesis is taking place.

Hi Kinder, what is the rate of baking soda to buffer the pH of should I just add a little. What do other greenwater users do? How much and how often do I need to do water chages as I've read that I should change 100% and seed with 10% of the old greenwater. This raises a couple of issues 1) cost 1200L x 3 ponds (soon to be 6) and the pH shock as the new water is pH 7 and the green water is pH 9.5, any thoughts guys?
Kinder
Hi nzkingyo,

I remember goldrush (a.k.a Doc) had posted, how no matter how much baking soda you put the max pH rise is 8.4. The buffer rate is about 1tsp per 20L. The water change rate would be once a week at least, depending on the greenness or intensity of the water.

Goto the Greenwater section under discussion area, there you will find a lot of info on greenwater changes and pH Buffering.

RafflesGold Forums > Discussion Area > Green Water, Filtration and Tank Setup:
http://www.rafflesgold.com/forums/index.php?showforum=5

Kinder
bekko
I would be afraid to run intense green water without aeration. Algae produce oxygen during the day. But they also consume oxygen around the clock and oxygen depletion at night is possible. Even a few hours of low dissolved oxygen can wreck a goldfish's immune system.

The aeration will also help replenish CO2 that is lost during the day and dampen the pH fluctuations.

-steve
nzkingyo
Great will try and add aeration to see if it lowers pH, do I run aeration 24/7 or just at night?

I'm not getting flucuations it tends to be between 9.4 and 10 all day. I have another 120L plastic bucket which I use to seed my green water in my ponds from and it has a higher load of fish than my ponds and I tested the pH today and it was 8.4 which to me is fine, this has been running for about 18 months and I have never changed the water, rain just tops up and overflows from time to tme.
bekko
I would be curious to know your alkalinity (KH). With pH 7 from the tap and a high pH maintained by CO2 depletion, you could be setting yourself up for a pH crash. The pH crash is usually accompanied by a phytoplankton crash. Baking soda, or a less reactive buffer like crushed shell, would be the remedy.

-steve
nzkingyo
Hi Steve, info from today pH at start of day 9.10, pH from end of day 10.13. Did a KH test and needed 10 drops to go quite bright yellow, as I have nver done it before it is a bit of a guess as too what colour yellow it is supposed to go. Tested water straight out of tap and it needed 8 drops to match the same yellow as my pond water. In both cases the first drop did not cause the sample to go blue it remained clear or ever so slightly tinted yellow.
BS worked a treat on my indoor aquarium as it was trending down towards 5, did a 50% water change and it rose to 6, waited 24hours then added a little BS and in rose to 7.4, very nice. Fish look happy.
Not to sure on what the advantage of adding BS to a pH that is already 9 - 10 will it pull it back to 8.4. Tried reading the threads in the posts listed but couldn't seem to find anything specifically like what I am experiencing a lot of the posts seem to be regarding getting the pH up and maintaining it at a higher level my problem is I want to get it down, any thoughts?
bekko
I don't know what eight drops means. Can you convert that to parts per million (ppm)?

Higher alkalinity and more buffering capacity will reduce the magnitude of the pH fluctuations so it will not get as high either.

Since your CO2 is not being replenished at night, I think you are going to need aeration and possibly more alkalinity as well. It would be easy enough to do a bucket test. Dip four containers of green water. Add aeration to one, add baking soda to the second, add aeration and baking soda to the third and do nothing to the fourth. About 1 gram baking soda per 10 liters of water.

http://openlearn.open.ac.uk/mod/resource/view.php?id=185884

-steve
Kinder
QUOTE(nzkingyo @ Mon, 15 Sep 2008 6:08 pm) *

Not to sure on what the advantage of adding BS to a pH that is already 9 - 10 will it pull it back to 8.4. Tried reading the threads in the posts listed but couldn't seem to find anything specifically like what I am experiencing a lot of the posts seem to be regarding getting the pH up and maintaining it at a higher level my problem is I want to get it down, any thoughts?


I buffer my outdoor pond setup to 8.4pH, and find the pH stays around that mark till its time to do weekly water change. Therefore i know my pH rang ....and dont have to introduce my fish to a lower pH i.e say 7pH after water change (as tap water is around 7ph mark). Early on when i was keeping fish in outdoor green water setup i did find similar fluctuations in pH from day to night time. Though after buffering i dont come across those high fluctuation from say 8-9pH.

Will keep a close eye on my pH for outdoor green water setup.....to see if it does fluctuate even after buffering.

ps: with the alkalinity test, you add drops till there is no further change in color, in this case to yellow. For KH test - 8 drops equals 143ppm (according to my test kit "Aquarium Pharmaceuticals", you might need to check with yours if its a different kit)

kinder
nzkingyo
Hi Kinder my test kit is the same aquarium phamceuticals so yes you are right 143ppm. Will do bekkos suggested test overnight and post the results tomorrow. Thanks - Steve
nzkingyo
Hi Bekko,

Overnight test results as follows:

BS + Aeration 8.40
BS + No Aeration 8.94
Aeration Only 7.87
Nothing 8.73

Will record results again at the end of the day and post. Looks like I need aeration though at this early stage of the investigation.

Cheers - Steve
nzkingyo
Overnight test results as follows: End of day test reults:

BS + Aeration 8.40 8.53
BS + No Aeration 8.94 8.96
Aeration Only 7.87 7.77
Nothing 8.73 10.00

Thanks for your help I will add aeration and let you know how I get on - Steve
bekko
It looks like diffusion is more important than respiration when replenishing CO2. Good job.

-steve
nzkingyo
It's been awhile since I last posted but I have been doing a lot of testing on BS buffered water and as you can see even when I have buffered with BS the pH still gets up over 9.

Results for a 4 days Sun 6.00am 8.00
12.00pm 8.83
6.00pm 9.28
9.00pm 9.15
Mon 6.00am 8.63
6.00pm 9.31
Tues 6.00am 9.14
6.00pm 9.41
Weds 6.00am 9.14
6.00pm 9.48
At this point I changed 80% of the water and pH was 8.68, today Saturday before I changed 100% of the water the pH was 6.99 and after the 100% water change 400L + 8L greenwater to seed my pond the pH currently is 7.82 with no buffering. So I will continue to monitor this over the next week to see what the out come is.

Thanks for all your help so far.
square_guy
Hi,

I am really out of touch with the technical side of green water, but if I remember correctly you should try looking into "carbonate system". You can probably get some answers there. If I remember rightly, sodium bicarbonate is weakly alkaline. There are other forms of carbonate at work here due to photosynthesis and respiration. You probably have to look into the chemical equation for photosynthesis and respiration to get a clearer idea as well.

Sorry, can't help much... it has been too long biggrin.gif
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