Added crushed coral to tanks... How long for it to stabilize PH/KH?

[Sandra the fish rookie]

I added coral to ALL my tanks! I added a bit at a time not to over do it all at once. 10G got 1 pound , 20 gallon 1 pound, 40G 2 pounds and the 5G has a little less than half a pound.. I added it after water changes. the 5 G has some in the filter and a bit in the tank. I am thinking he needs more in his tank. The PH is still dropping to around 6.6 - 6.8 ish... I have hard water. 280... 

Should I add more? Wait??? ugh.. I do water changes every 2 weeks sometimes every 3 weeks if all is good chemistry and looks wise. 

 

[Just some nerd]

Great question! Jennifer Lynx also suggests 1/2 cup per 20 gallons to raise and buffer PH which is far less than AC. 🤷‍♂️

[CT_]

I think the rate it dissolves at depends a lot on, ph, temperature and flow, maybe hardness too (especially calcium I'd think).  So you won't get a solid answer anywhere.  You can sort-of upper bound that time by your water change frequency (and quantity) since anything that changes "slower" than that is unlikely to have a big effect on parameters

[Biotope Biologist]

To bounce off @CT_ the hardness of your water affects how much and how quickly your calcium carbonate will dissolve into the water and thus how effective it will be at buffering your pH. Since you have a high gH in your tap water crushed coral is less effective at dissolving into the carbonate ions (kH) . The water already has alot of calcium and/or magnesium (gH) and therefore the equilibrium reaction cannot take place as quickly or effectively. 

 

For this reason I would recommend using carbonate salts in conjunction with your crushed coral and water changes to get the desired kH levels

[Sandra the fish rookie]

So based on the comments, I can hold off on adding anymore coral for now and increase my water changes. Will increasing my water change frequency have an impact on my Nitrates? I suppose as long as I don't clean my filters it should not be an impact.. am I accurate with that one or WAY off.. it too me SOOO long to see nitrates.. I never want them to go away..LOL

[ARMYVET]

Changing water will remove Nitrates...thats one of the purposes for doing water changes in the first place is to remove nitrates. 

 If you want to see the crushed coral work a bit faster it needs to be put in an area of higher flow than just sitting on the bottom of the tank.  The acidity of the water is what breaks it down and if you have good flow over it ...it works more efficiently.

[Biotope Biologist]

Sorry I see how my comment could be mistaken for more water changes. Always hard to convey intent in a text box. While it is recommended to do small water changes once a week or twice a week, my intent was that in order to increase kH in hard water you have to add carbonate salts to the water as crushed coral increases both kH and gH simultaneously. Therefore, if your water is high in gH your crushed coral will not dissolve as fast.

 

Let me know if you would like me to explain this chemical reaction further. I think at this point it would be helpful for me to make/ find a helpful video explaining it as water chemistry confuses even chemistry students in college who have studied it for 2-3 years.

[Sandra the fish rookie]

@Biotope Biologist That would be helpful. I guess I could put it in my filter for better flow like @ARMYVET mentioned. Non of my fish seem to be bothered by it at all. I thought by increasing my PH and KH it would help stabilize my aquarium better resulting in less alae on the plants. I had another post where Cory recommended using crushed coral to help stabilize my PH. Again, I have no idea what I am doing. I just hate disturbing my aquarium to change water when it looks clear, fish are thriving, plants are growing, and parameters are within normal range. I just want what is best for the animals and ecosystem .. but don't want to over do it and send everything out of wack.

[ARMYVET]

On 6/17/2021 at 3:42 PM, Sandra the fish rookie said:

@Biotope Biologist That would be helpful. I guess I could put it in my filter for better flow like @ARMYVET mentioned. Non of my fish seem to be bothered by it at all. I thought by increasing my PH and KH it would help stabilize my aquarium better resulting in less alae on the plants. I had another post where Cory recommended using crushed coral to help stabilize my PH. Again, I have no idea what I am doing. I just hate disturbing my aquarium to change water when it looks clear, fish are thriving, plants are growing, and parameters are within normal range. I just want what is best for the animals and ecosystem .. but don't want to over do it and send everything out of wack.

If you can put the crushed coral in the filter do so ....then wait at least 2 weeks with any water changes and see how its progressing. Message back and give us your water parameters in 2 weeks and we can go from there as to the next step. 

[Ceej]

I am having a similar issue, thanks for this post. My 10G tank is consistently showing low pH, as low as the API test will show, so it could perhaps even be lower. I've used bottled additives to increase the pH but within a few days it always drops back down. I'm wondering what the cause would be?

When I tested straight tap water (no dechlorinator) I get a pH reading of 7, perfect. Can dechlorination lower pH?

Anyway, aquarium water pH is consistently 6, so I crushed down some seashells with a mallet, placed in a mesh bag and placed in the tank (no space in the filter itself, unfortunately) but I didn't realize that two weeks is the kind of time frame to see a change.

Edited June 18, 2021 by Ceej
typo

[ARMYVET]

On 6/18/2021 at 7:49 AM, Ceej said:

I am having a similar issue, thanks for this post. My 10G tank is consistently showing low pH, as low as the API test will show, so it could perhaps even be lower. I've used bottled additives to increase the pH but within a few days it always drops back down. I'm wondering what the cause would be?

When I tested straight tap water (no dechlorinator) I get a pH reading of 7, perfect. Can dechlorination lower pH?

Anyway, aquarium water pH is consistently 6, so I crushed down some seashells with a mallet, placed in a mesh bag and placed in the tank (no space in the filter itself, unfortunately) but I didn't realize that two weeks is the kind of time frame to see a change.

What substrate are you using....something is breaking down and leaching into the water and driving down the ph.  Also What is the KH reading in the tank?  If it is at 0 it would not take much at all to cause the ph to crash down.  

[Ceej]

I do not yet have a KH test, but the pH has improved over the last three days from 6 to 6.4, so I am hoping it will continue to trend upwards. My substrates is rainbow colored stock aquarium gravel from PetCo. This is a concession to my daughter, lol. I would love a more naturalistic aquascape.

I tried finding some space in Aqueon QuietFlow 10 for the baggie of crushed seashells, but no luck. I am thinking maybe just mix in some pH-raising gravel of some sort. Any recommendations?

Oh, and I also turned off my bubbler to see if that helps reduce the pH. I'm thinking it could also be the giant red stone. Branch was boiled and scrubbed multiple times to remove tannins.

Occupants right now are two neon tetras and 3 female guppies. I have read that guppies greatly prefer and react well to higher pH and harder water, so I'm on the verge of removing the rock, I think it really must be the culprit.

Edited June 21, 2021 by Ceej
Add image, more details.

[Biotope Biologist]

The rock usually will not change pH in the water. If anything it may add some trace minerals but that's about it. Your wood will reduce pH in the water but tannic acid is a weak acid and you can very easily counteract that.

 

An airstone will not reduce pH it only serves to oxygenate the water and create disturbance.

 

You can buy aragonite sand, but mixing it with pea gravel can lead to compaction so I wouldn't recommend it.

 

You can put the bag of crushed coral in the tank somewhere out of sight using a suction cup or clip. Although again without knowing your kH and gH values this may be an ineffective pH buffer. If you do not want to purchase these quite yet most pet stores test water for free. Bring them a sample of aquarium water and tap water and give us those results and I can make further recommendations.

 

Guppies are an extremely hardy fish that can live anywhere from full seawater to a freshwater swamp where pH is low so if it's just for the guppies don't worry to much about the water parameters.

[Ceej]

What exactly is 'compaction'?

[tolstoy21]

On 6/18/2021 at 7:49 AM, Ceej said:

When I tested straight tap water (no dechlorinator) I get a pH reading of 7, perfect. Can dechlorination lower pH?

Water with no KH (or low KH) can (and I think will) equalize at a neutral Ph of 7.0, especially when aerated with an air stone or agitated with a powerhead (or anything that promotes surface gas exchange).

Water straight from my well has a Ph of 5.5 and zero (or slightly above zero) Kh. When I let is sit in a barrel for a day with a running air stone the Ph equalizes at 7.0.

The problem with having little to no buffer in water (low Kh) is that anything can suddenly swing the PH down in your aquarium (Co2, fish waste, decaying matter)  causing the Ph to plummet. 

The idea of 'buffering' is that this helps stabilize those swings. The Kh, in essence, keeps your Ph from suddenly being influenced by some other factor and acidifying the water.

The Ph you want to target really depends on the species of fish you're keeping. I would guess most 'community' planted aquariums run, on average, somewhere between 6.5 and 7.6. But this is just a guess.  African Cichlid tanks run higher to accommodate for the preference of those species.

Ph and Kh typically don't cause algae. However, a lack of GH can cause mineral deficiencies in aquatic plants. 

What you want to achieve in regards to Ph is stability (the presence of some KH helps with that stability), and not a specific number, so long as you're somewhere in the general ballpark of what your fish 'prefer', and avoid extremes.

 

Edited June 22, 2021 by tolstoy21

[Tanked]

On 6/22/2021 at 6:55 AM, Ceej said:

What exactly is 'compaction'?

Substrate of the same general size will always have gaps between the pieces.  When adding smaller pieces such as sand, the gaps will become filled, or compacted, locking the pieces together. A gravel road is a good example.

[Biotope Biologist]

On 6/22/2021 at 3:55 AM, Ceej said:

What exactly is 'compaction'?

Sorry I probably should have omit that word as I don't believe it's used often in the aquarium world.

 

But the literal definition is to make more dense with the exertion of force. In this case the constant exertion of force by the water column will cause the 2 different sized medium to settle and become more dense- like concrete.

 

It's bad because it can trap gasses and water and make your fish sick when the substrate becomes agitated

[Ceej]

Well, the addition of the crushed shells in a bag seemed to have been helping pH, which moved from 6.0 to 6.6 ... but then plunged yesterday back to 6.0 again. The tank is very newly cycled, a week in, so there are still plants that are struggling. Algae has backed off significantly after I removed it. I think the drop could be due excess food from overfeeding and maybe some of that decaying plant matter that I've been vacuuming up. Thanks to everyone for the great advice.