Why a PH drop despite aged water, regular changes, 9dKH?

[Sasha]

37 gallon grow out tank containing 20 two inch fry/juvies (including tail); Penguin 200 HOB filter with pre-filter on intake tube (cleaned at least daily) plus Eheim substrate pro media; one additional sponge filter; 8-12 hour aged, circulated, heated water (50/50 mix of well water and RO); 75-80% water changes at least once and usually twice a day.

Ammonia 0, Nitrite 0, Nitrates less than 5 ppm 12 hours after 75% water change, 9 dKH. Temp 82 degrees.

Feeding: mostly freeze-dried blackworms, 1 feeding of mysis shrimp daily, 1 feeding of spirulina brine shrimp daily. Feed approx ev. 2-3 hours.

Aged water is at PH of 8.2 going into tank. 12 hours after water change the PH in the tank drops to 7.8-7.9. Another 10-12 hours and the PH drops to 7.4.

I would think that the KH would be high enough to keep the PH stable??? Why the PH drop?

I work full time and to do even more water changes is not really feasible. I suction out debris twice a day in addition to the water changes and filter rinses.

Thoughts or ideas? Thank you.

[Len]

How are you aging your water and for how long? If that is the only drop you have, it isn't enough to be concerned about.

[Second Hand Pat]

Sasha, are your fish reacting to the PH drop? If not like Len says, should not be concerned about it as the drop happens over a long period of time.

[Sasha]

Thanks for the quick responses. My concern is that when I do a large water change, I'm raising the PH significantly from 7.4 to 8.1 or so in the tank. During and shortly after a water change, the fish sort of just float around and some of their eyes go into a "blank stare." And their breathing rate pics up a bit. It takes a little while for them to resume a normal swimming pattern.

I age my water in a large brute trash can with a heater and an air stone. The water is aged at least 8 hours, typically 12-20 hours.

[Len]

Sasha, are you using a dechlorinator? If the water is from a municipal source, there may still be some additives (chlorine/chloramine /flouride) in it. To age your water you need to use sufficient agitation and allow sufficient time for the additives to dissipate and you still may need to use something like prime or safe depending on what is in it. Regardless of that 8 hours is definitely not long enough, 24 would be more reasonable. The difference between 7.4 and 8.1 isn't a big swing, so I doubt that is causing them any distress. If you are only aging to prevent ph swings, I'd just use straight tap with a dechlor and save the extra time and effort. You mentioned they act funny after a change, how long does it take them to settle back down? If only a short while, they may just be a little agitated by the commotion. If that's the case, in time they will tend not to much care as they'll get used to the routine.

[Sasha]

I use a 50/50 mix of well water and RO water. I do have some ferrous iron in my well water, which settles out during the aging period. I only dose with Prime if the water in the aging bin is a bit cloudy due to the hardness of the water not fully settling out.

The PH of the aged water does not change further after the 8 hours of aeration; can you help me understand why waiting longer is a good idea? If I need a full 24 hours to age the water, then I am limiting myself to one water change a day vs often performing 2 a day.

The fish usually act normal about 10 mins after the water change.

[Len]

I was assuming you were using municipal water that had chlorine or chloramine in it. If that were the case, it would take longer to age. In your case, your fine. Also if it takes them 10 mins to settle down, continue what you're doing and you'll be fine.

[DiscusDrew]

I would increase the buffering capacity of the water, ie the kh or carbonate hardness. Unlike what's said above, I do find that to be a large enough swing to cause stress amongst discus especially if your doing large water changes. My Ph swing is less than that but I age specifically to get rid of the swing in Ph because it caused numerous problems. Why are you using RO period? Just out of curiosity.

[Sasha]

Thanks to all for your responses.

DiscusDrew, I'm curious as to the dKH of your water. Is it significantly above 9 dKH? I had thought that the general recommendation for discus keeping (not breeding) was about 6 degrees.

I use a portion of RO water to help "cut" or reduce the amount of iron that I have in my well water. I know that too much iron is not beneficial for fish health. My mix is not too scientific - I just felt that lessening the iron content of my well water would provide a better environment.

I do add a large WonderShell to the tank, so that as the calcium and magnesium are depleted in the tank, they are automatically replenished by the slowly dissovling WonderShell.... Or at least that's what the manufacturer and other fish hobbyists claim.

[Sasha]

Is there anything else besides KH that would factor into the PH drop? Is it simply a matter of too much waste "using up" the buffering capacity (KH) of the water? Or might there be other factors that would cause a nearly 1 point drop in PH over the course of 20-24 hours?

[DiscusDrew]

The thing is your water changes should be eliminating that drop at the rate your doing them. I'm not saying using RO is bad, I have very hard water with Ph around 8.2 after aging, kh around 7. I only use RO when I breed, then go right back to aged tap. Have you tested your KH? That is the only thing that would make sense to me if all info above is accurate.

[DiscusDrew]

Nvm I just ready that your Kh is 9, ok for those that know my general advice on water perameters, it usually is to not mess with anything, dont add anything, dont subtract anything, nothing, unless absolutely necessary. Given the issues you are seeing though, perhaps it IS necessary. If you want to remove the iron content (not saying its a bad idea by any means) you have two options, RO unit, or iron filter (very spendy). SO, beings as you already have an RO unit if it were MY TANKS, this is what I would do. I would drop reconstituting with tap entirely over time, I would slowly get them into a 100% RO mix using RO right or another similar quality product to reconstitute the water. This would need to be done gradually most likely as it will likely lower your ph to around 7.0 (depending on water conditions). My point being, something is making your Ph drop and with your Kh where it is it seems illogical that it should drop as it is, unless there is one hardcore bio process going on in the tank, which again, doesnt make sense because of your W/C schedule UNLESS you are not cleaning the tank regularly and filter media as well. So thats the first thing to check, after that I think we may need to look at doing something entirely different with your water, as there should not be a Ph drop in the tank that significant. And in my opinion that is a significant drop over a 24 hour period. JMO, and yes I realize this would take some work, but you already have an RO unit and I know many people on well water that do a 100% RO mix with RO right or another reconstituant, with great success. Let me know what you choose to do and Id be more than happy to help.

[Len]

Drew, I have to disagree. This is over analyzing the situation. Her discus act different for 10 minutes after a water change, that's not a large concern. One of the methods Andrew Soh recommends to induce spawning is dropping ph by a full point for a day then bouncing it back up a full point for a day and repeating the cycle multiple times. If she were seeing a larger swing then it could be a concern but not at this rate. If it makes her feel better then she could age longer to allow dissolved gas to escape and the swing would probably go away. 8 hours isn't enough for that to happen.

[DiscusDrew]

Generally displacement of co2 will cause a rise in Ph not a lowering. I know we disagree, that was my point :) and that is ok. We aren't talking about a week or two to induce spawning, were talking daily... Forever... Which I personally would not accept. At that, it is the op's decision. I prefer my water stay extremely consistent and it has given me great success, I also generally believe in adjusting or changing as little as possible with your water parameters. But a one point drop every day, that I would not accept, its not like were talking about doing it intentionally for a fish that is comfortable and stable to induce spawning. Regardless, we have our views and my intention is not to debate them. I've never seen Ph drop as a result if aging... So someone would have to explain that one to me.

[cjr8420]

Is there anything else besides KH that would factor into the PH drop? Is it simply a matter of too much waste "using up" the buffering capacity (KH) of the water? Or might there be other factors that would cause a nearly 1 point drop in PH over the course of 20-24 hours?my guess is very dirty substrate have u skipped a WC for a couple of days does it continue to drop further.


Drew, I have to disagree. This is over analyzing the situation. Her discus act different for 10 minutes after a water change, that's not a large concern. One of the methods Andrew Soh recommends to induce spawning is dropping ph by a full point for a day then bouncing it back up a full point for a day and repeating the cycle multiple times. If she were seeing a larger swing then it could be a concern but not at this rate. If it makes her feel better then she could age longer to allow dissolved gas to escape and the swing would probably go away. 8 hours isn't enough for that to happen.+1 on over analyzing but off gassing only causes ph to go up not go down.

[DiscusDrew]

Note where I say "UNLESS you are not cleaning the tank properly and filter media as well".

[Sasha]

Thank you to all for your thoughts and advice.

The tank is bare bottom and all tank surfaces are wiped clean with a paper towel at every water change.

One thing that I might need to "up" is how often I change out my HOB (Penguin 200 Bio-wheel)filter cartridges. I do not use carbon. I use the Marineland filter cartridges, which I slit open along one side, empty out the carbon, and then place in the filter. I rinse and squeeze out the filter cartridge about every 2nd day using lukewarm well water. However, I only replace the cartridge with a new one about once a month, or when I can't see through the filter when holding it up to the light.

[brianyam]

My view is, keep things simple. Don't try and "control" PH. It will cause more problems than benefits. Don't add anything to buffer this or that. Your chasing.

Normal tap water PH won't change rapidly, fish are fine as long PH is in a stable range. Look, PH and water temp changes in the wild all the time. Actually, that is how people who breed plecos, sting rays..etc induce breeding. They actually spray the tank with cold water (to copy rain water), and it actually induces rays to breed pretty much instantly. I have seen it with my own eyes. It is pretty cool. I know some love to age, but I don't do it, and I don't see my fish acting any different (gasping for air, stressed). My fish actually continue to try and eat while I do a WC and clean up, it is actually annoying as they get in the way of what I am trying to do. I have wilds so maybe it is different.

Keep it simple. Don't get too paranoid. Your fish won't die from non aged water or slow PH changes.

[Elliots]

I do not think this is a significant problem or your answer but why don't your rinse and squeeze out your filter cartridge using tank water that you are going to discard because you changed the water? Don't rinse with well water.That may also be affecting the BB in the filter.

[Second Hand Pat]

Elliots, what is wrong with rinsing with well water if it contains no chlorine or chloramine?

[DiscusDrew]

Nothing is the answer to that... This Ph drop is baffling after that last post, I'd be making sure my test kit isn't whack. Fyi I don't even test my Ph unless something is wrong.

[Elliots]

I agree with DiscusDrew and Second Hand Pat, nothing is probably wrong with using well water. I was just suggesting a possibility. I should not have said "Don't rinse with well water", I should have said maybe that is a problem but probably not. Sorry, I misspoke.

[Elliots]

I am having a bad day at work. What I really wanted to say is why don't you try rinsing your filter in old tank water to see if that makes a difference. It probably does not but maybe it is worth a try.

[DiscusDrew]

As habit I totally agree, always best to use aquarium water in general. Then you have nothing to worry about. The only risk in using well water would be if it was at high or low temps which could cause BB die off. Like I said though my friend, always safest to use aquarium water, in that you are correct.

[Tommo]

Having read through the whole thread I would like to just add my 2 cents worth:

Swings in pH
I notice members have expressed differing views regarding the swing in pH values from 8.2 to 7.4 in a 24 hour period – some members don’t see this as being significant while others hold the opposite view. However, nobody has explained the fact the pH is measured using a logarithmic scale.This means each whole pH value below 7 is ten times more acidic than the next higher value. For example, pH 4 is ten times more acidic than pH 5 and 100 times (10 x 10) more acidic than pH 6. This is also true for pH values above 7, each of which is ten times more alkaline than the next lower whole value. For example, pH 10 is ten times more alkaline than pH 9 and 100 times (10 x 10) more alkaline than pH 8. It therefore, follows that when carrying out a large water change, using the values stated from pH 7.4 to pH 8.2, the fish in question are being subjected an 8 times increase in alkalinity – I’d say that was significant . . .

As a general rule acidophilic fish are better able to ‘tolerate’ significant drops in pH values but less able to tolerate significant increases in pH. I have to say that I’m concerned over the described behavior of the fish e.g. the fish “sort of float around and some of their eyes go into a “blank stare” . . . act normally after 10 minutes.” I suspect that their delicate gill filaments are reacting to the sudden increase in alkalinity when subjected to the large water changes.

[B]KH values and drop in pH
I’m presuming the KH value of 9 is the value when taking a reading from the aquarium? (If this value is the reading before mixing it with the RO water the KH will clearly be lower).

I strongly suspect that given the stocking density and the heavy feeding regime that the ‘bio-system’ is not able to cope with the organic load despite the KH buffering effect. ..

You appear to have to clean / rinse your filters on a frequent basis which poses two questions:

1. Are the fish consuming all the food that they are being offered or is a significant amount being sucked up by the filters? If this food is being sucked into the filterers not only will it be decomposing in the medium but it will also be reducing the flow rate through the filter and therefore reduce their biological filtering capacity. Check the surface of the sponge(s) – do they have a thin white coating of ‘biofilm’? If so, this is an indication of overfeeding . . .

2. By rinsing / cleaning your filters too frequently you will also significantly reduce their biological effectiveness. I personally would only ever rinse filters in the water that is siphoned out during water changes which will help preserve the established aerobic bacteria. Using other water sources will kill off at least some of these ‘delicate’ bacteria.

Your filters should only need rinsing out on an occasional basis if you have a ‘balanced’ feeding regime. Furthermore, if you smell them when you are rinsing them out (in tank water) they should have a pleasant ‘sweet’ smell indicating that they are populated with aerobic (rather than anaerobic) bacteria.

Water ageing
I agree with most members here that you need to age and aerate you water for a full 24 hours. However, given the fact that your well water has measureable amounts of iron in it I would seriously consider using reconstituted RO water . . .

[Sasha]

Tommo,
Thank you very much for your detailed and clear response.

To answer your questions:
- yes, the 9 dKH reading was taken from the aquarium (not the aged, clean water used to refill the tank during a water change)
- I unplug the filters for 10-15 mins during feeding time. Typically they will not eat all of the food during those 10-15 mins, but they will eat a good portion of it. After 30-45 mins, nearly all of the food is gone (at least the freeze-dried blackworms, which is their staple food and really the only food I can get them to eat besides frozen spirulina brine shrimp. I've tried flakes and pellets over the last month and they won't touch them). Some food certainly gets sucked into the pre-filter that I have on the filter intake tube, which I rinse 2-3 times a day. When I rinse the filter cartridges, I do not see food particles there. Perhaps I am overfeeding a bit? I have raised this spawn of fish and perhaps I am too eager to ensure that they have a good growth rate. My pre-filter is a light color, so it's hard to answer your questions about the possibility of a biofilm. Certainly the pre-filter gets quite dirty, which is why I rinse it so often.

I will take the advice of rinsing the filter media in tank water removed during the water change process. I will also increase the time I age my water, although this will have an impact on how often I can perform water changes on all of my tanks.

How often do you recommend that I rinse out the filter cartridges?

[Tommo]

Tommo,
I will take the advice of rinsing the filter media in tank water removed during the water change process. I will also increase the time I age my water, although this will have an impact on how often I can perform water changes on all of my tanks.

How often do you recommend that I rinse out the filter cartridges?

The main purpose of prefilters is to provide a 'barrier' to protect the main filter medium from clogging up with the larger particals of food and organic waste. The main filter should be utilised as a biological filter and should very rarely be cleaned - there are many products you can purchase that are suitable for this purpose (I use plastic bio-balls). Just clean your prefilters. If you want to filter through activated carbon, it may be easier to use a separate internal box filter which you can change without disturbing your biological filter(s).

If you moderate your feeding regime and increase the efficiency of your biological filters the reduction in water changes should be 'okay'. You do however, have a lot of fish to attempt to grow on in a 37 gallon tank. I would suggest you also need to consider reducing your stocking level to say 10 fish.

[Sasha]

Thanks again, Tommo. I do have Eheim Substrate Pro as part of my filtering media. Perhaps I need to refresh it or add more to my HOB filter.

My plan is to sell or donate the fry very soon, so the stocking level in the tank will not continue for much longer. I want to make sure they are fully healthy and I think they need to grow out just a bit more before they are ready to move on to a permanent home.

[DiscusDrew]

Screw the cartridges!!! haha get rid of them, all my hobs dont have any whatsoever, they are just stuffed with bio-media and honestly this could be part of the core of one of your issues, though it sounds like things are at least somewhat the way they should be. Prefilter on intake, rinsed at least daily, media inside of hob should then not have very much waste accumulating and thus SHOULDNT have to be cleaned very often (mine is done monthly) but this is depending on the factors listed above (Tommo I love your response btw). If they are not consuming ALL of what is fed within say 45 minutes or so then something isnt quite right, especially with the stocking density of the tank. Worst case scenarioo what you may consider and may help drastically is splitting the batch of youngsters. This will cut your bio-load in half, having a huge impact on the nitrogen cycle of the aquarium which should kill your current issue with drop in Ph. Just a thought.

[DiscusDrew]

Whoops just finished reading the rest of the thread, looks like this has already been discussed.