Drop In Kh.

[pob_16]

Hi all.

I have a question about the KH of my water. I am currently in the middle of a fishless cycle, waiting for NH3 and NO2 to go in 12 hour stage. Now the KH of my tap water is 170ppm/9.5deg but in my tank it has dropped to 50ppm/2.8deg. The tank is fairly heavily planted and I am injecting pressurised CO2.

I am a bit worried if the KH has dropped so much would this mean pH control would be difficult (currently at 7.0) or is this drop in hardness normal during a fishless cycle? I have not done any water changes since starting the cycle about a month ago.

Any advice appreciated.

 

[Thommo]

Hi all.

I have a question about the KH of my water. I am currently in the middle of a fishless cycle, waiting for NH3 and NO2 to go in 12 hour stage. Now the KH of my tap water is 170ppm/9.5deg but in my tank it has dropped to 50ppm/2.8deg. The tank is fairly heavily planted and I am injecting pressurised CO2.

I am a bit worried if the KH has dropped so much would this mean pH control would be difficult (currently at 7.0) or is this drop in hardness normal during a fishless cycle? I have not done any water changes since starting the cycle about a month ago.

Any advice appreciated.

Hi pob_16,

I have gone through the same thing as yourself. Although ppm doesn't mean much to me as I test in dkh. It is common for a fishless cycle to go through a Ph crash. This is due to the high nitrAte output during the cycle. NitrAte reduces the buffer (KH) which in turn reduces your PH. Unfortunantly most consider a PH of 6 to cause the cycle to stall. If you are testing daily I would recommend doing a 50% minimum water change to help reset the KH as it has been depleted. If your KH is low out of the tap you may have to do a water change everytime the PH drops close to 6.

As a guide the higher the PH during a fishless cycle the better for the Bacteria. I'm sure someone else will come along and recommend you add bicarbonate soda which will increase your KH buffer and your PH to a better range for the Ba. I myself have done this.

I assume you must have a decent test kit as you are posting KH stats. A full detailed report of stats, when you started etc e.g.
Day X – Fishless Cycle on X litre tank

Test 1 – Time of test
pH – X
Ammonia – X
Nitrite – X
Nitrate – X

Details of action on the tank, for example ‘Ammonia topped up to 5ppm’

Test 2 – Time of test (usually 12 hrs later)
Ph – X
Ammonia – X
Nitrite – X
Nitrate – X

Details of action on the tank
This
will benifit all on the forum to be able to help you more affectivly. There are some very knowledgabel people on this site in reguards to fishless cycling so you have come to the right place.

CHEERS
Thommo

 

[pob_16]

Thanks for the reply Thommo.

I have been testing the water daily, and since the nitrites have been processing, testing every 12 hours. My NitrAte levels are off scale high, but I have been reluctant to do a water change as I have read somewhere that if a water change is done too early in the cycle it could unsettle the bacteria I have been patiently growing. Is this correct?

The pH of the water has been slowly dropping from 8.0 down to 7.0 along with the KH which co-insides with the nitrate levels increasing in the water. What you have said about a water change makes sense about avoiding a pH crash, but will the water change effect my cycle?

I feel that I am so close to finishing the cycle and would be devastated to go back to square one.

If needed I can post more info on my cycle, but that will have to wait till tomorrow as I am at work at the min.

Cheers.

 

[OldMan47]

A water change will not harm the bacteria. You need to control the KH so that you don't end up with a pH crash that stalls your cycle. The pH will continue to drop slowly until the KH is near zero, at that point it will fall right off the cliff and end up below 6. We read about it happening every day. The nitrates that form from the bacterial action are acidic so once the buffering capacity is gone the pH crashes. If your tap water is close to an 8 pH wth a hardness of around 10 degrees, it will easily correct the drop you are finding yourself in.

 

[waterdrop]

Yes, agree with the others. Not only does a water change during the later stages of fishless cycling not cause problems, if often kickstarts a cycling process that has been getting slower.

~~waterdrop~~

 

[pob_16]

Thanks for the advice.

I did a 50% water change yesterday then added the ammonia and after 12 hours did a full set of tests.

Day 26. 10:00

pH back up to 7.5
NH3 0ppm
NO2 0.5ppm
NO3 80 – 160ppm (difficult due to the close colour changes on the chart)

KH back up to 110ppm or 6.2deg
GH 8.9deg

Will do another water change today to get the nitrates down. As I said it’s a bit difficult to get an accurate reading as the chart I am going off goes up in different shades of red. It could well be off the chart so I may as well get these readings down as they will need to be anyway.

Again thanks for the help, looks like you have helped me avoid a pH crash and if nothing else the water is no longer looking like pea soup!

 

[wolfwolf]

What is the pH of your tap water? Do you have a drop checker to check your co2 concentration? I'm just thinking that a pH of 8.0 with co2 addition seems high.

 

[pob_16]

Tap water pH is 8.0. Drop checker is in the post and shoud arrive tomorrow, already have my 4dKH water and pH test kist on stand by. My tank is an 80 us gallon and CO2 is currently around 3 bubbles per second injected via a powerhead. Does this seem high or about right?

 

[waterdrop]

You actually sound like your fishless cycle is proceeding pretty well.

I'm going to bring up an "aside" for you: I don't think its been mentioned that fishless cycling and planted tanks don't always mesh together as smoothly as one might think. A lot of the planted tank folks hardly believe in doing fishless cycling even, although probably there is not uniformity about that. What happens is that a heavily planted tank works to perform the same service for you as nitrification in a biofilter does, but a really good planted tank does it really in a much more natural way. Plants will absorb ammonia (that's their first choice) and also to varying extents nitrite and nitrate. When you have a *lot* of plants, they will alter the readings of ammonia and other things that you are using as feedback for understanding your fishless cycle (ie. you think you've got a lot of A-Bacs eating your ammonia but really the plants are eating it!)

In most circumstances (hopefully yours) any contributions by the plants will just slow the develpment of the biofilter, but eventually you will still have a nicely cycled filter. The ideal planted tank has a decently cycled biofilter helping out the natural cycling the plants are doing. The rub comes for us beginners at plants who are not good at keeping them alive (this is how I see it but remember I'm a beginner too and the plant guys of course see it differently because they know how to keep the plants going great) and if too many plants die and the nitrification capacity of the biofilter has not really built up to match the full fish bioload, then you can get in to cycling situations, especially since plant death adds debris and ammonia load despite you trying to get the dead leaves out of there fast.

I believe the ideal planted tank cycling meshes very nicely with an ideal fish-in cycle. The very heavily planted tank is established and a very few fish are introduced such that if one can detect any ammonia or nitrite at all, its at trace levels. This very light load goes along for a month or so and then the stocking is raised very gradually and usually stops way short of the load that traditional trop enthusiasts would be heading toward. Again, just my beginners interpretation of things, but thought it might interest you.

~~waterdrop~~

 

[pob_16]

Thanks for that Waterdrop, its something I will look into over on the planted forum.

I suppose since I have had the plants in from the start and they have been growing quite impressively (having to prune every week to stop it looking a complete jungle!), I won’t really know what is processing the NH3 and NO2, them or the bacteria in the filter. As you say, as long as the plants stay alive, it shouldn’t really matter, but that’s the trick isn’t it. I would say I have “a lot” of plants in the tank, but what I mean as a lot, others may not. I would say about 40% to 50% of the sand is planted which I think is a lot, but then looking at some of the photos on the planted forum, it doesn’t compare!

 

[waterdrop]

If it doesn't look thick with plants like the planted tank forum then the filter is probably getting cycled pretty well I'd guess.

~~waterdrop~~

 

[wolfwolf]

Not sure how fishless cycling affect a tank because I've never done it. But the Co2 should drop your pH by 1 (at 30ppm) depending on your water hardness it could be more or less.

Just thinking out loud but your plants may be growing very well now becuase of the ammonia addition to cycle the filter. So when the cycling is done and ammonia is close to zero.... what does that mean for the plants? Slower growth? Algae? Probably a better question for the planted section.

 

[OldMan47]

It won't bother the plants at all. Right now they are getting a very high 5 ppm followed by a drop to near zero, then another spike. When the cycle progresses a bit further, they will see a spike in ammonia followed by hours on end of nothing at all. When fish go into the tank, there will be a constant low level supply of ammonia and the plants will love the steady supply instead of all the sharp spikes.
WolfWolf is right that 30 ppm of CO2 should drop pH by about 1 pH point. When you measure the pH before and after turning on the CO2 valve, you can get the same information as you get from a drop checker. That is basically all a drop checker does, it indicates the CO2 concentration averaged over the last few hours.