Alk low during cycle?

[cemyth]

Right now I am cycling my tank and decided to start testing all my water parameters and noticed my alk was really low. I tested it at 5.5dkh a few days ago. To get it up to more normal levels I have been slowly dosing soda ash and as of today I am at 7.4dkh, however I have noticed it wants to drop. Could this be form the nitrogen cycle at work or the decaying pieces of shrimp used to start ammonia off? I know it may not matter what the alk is during the cycle but I just feel better knowing that it is at least in normal range. Any thoughts? ;)

Current water parameters:
SG: 1.026
PH: 8.2
Alk: 7.4dkh
NO2: 0ppm
NH3: 0.50ppm
Ca: 450
Mg: 1440
PO4: <0.05 maybe a little more or less, haven’t tested it in a few days
NO3: <0.25 maybe 0

[disc1]

That process of cycling in tends to pull alkalinity and pH down. It is due to the decay process. I wouldn't worry too much with alkalinity until you've finished the cycle and are getting ready for corals.

[tmz]

I wouldn't dose during cylcing,personally.or worry abut alk very much. Extra water surface agitation might help slow down CO2 accumulations which may be affecting the pH and alk .

[cemyth]

That process of cycling in tends to pull alkalinity and pH down. It is due to the decay process. I wouldn't worry too much with alkalinity until you've finished the cycle and are getting ready for corals.

That is what I thought. Just wanted to get an experts opinion.

Would there be any reason I couldn't try and keep Alk just above 7dkh? The reason I ask is a do have a few pieces of live rock for seeding the dry rock with life on them and I don't want to stress them out too much.

[disc1]

That is what I thought. Just wanted to get an experts opinion.

Would there be any reason I couldn't try and keep Alk just above 7dkh? The reason I ask is a do have a few pieces of live rock for seeding the dry rock with life on them and I don't want to stress them out too much.

Pods and stuff on the rock won't really care much if it falls off a bit. But there is certainly no harm in keeping it up.

[cemyth]

Pods and stuff on the rock won't really care much if it falls off a bit. But there is certainly no harm in keeping it up.

Thank you!

[cemyth]

I wouldn't dose during cylcing,personally.or worry abut alk very much. Extra water surface agitation might help slow down CO2 accumulations which may be affecting the pH and alk .

I understand what you are saying. (Had to read up a little) I will increase the air flow and surface agitation to provide more O2 for the aerobic bacteria and CO2 gas exchange.
Thanks!

[tmz]

The surface agitation will facilitate gas exchange, that's right.The O2 would help the aerobic bacteria that oxidize ammonia to nitrite andnitrete to nitrate.. The anaerobic activity occurs when O2 is low in their location and bacteria turn to NO3(nitrate) for O2 leaving N which combines with N to make N2 notrogen gas which bubbles out of the tank. That second stage of the cycling process is known as denitrification. In any case extra air exchange is helpful.

[mchammer]

I'm having the same problem but my tank has already cycled. My water parameters are as follows:
SG-1.023
PH-8.14
Alk-6.1dKH
Calcium-390
Mag-1500

My SG was 1.025 as of 3 days ago but for some reason they dropped. I did a water change last weekend of 20%. Everything was fine Alk-7.2 Mag-1300 and Calcium-420 I also added the rest of my fish and CUC as well as some coral. Could that change water parameters that fast?

[bertoni]

The SG can drop only if fresh water is added to the system, or if the water change was done with low-salinity water. I'd check for measurement problems first, and I might add some baking soda to increase the alkalinity. This calculator might help:

http://reef.diesyst.com/chemcalc/chemcalc.html

I'd dose the alkalinity up to at least 7 dKH.

[mchammer]

bertoni you are right about the saltwater mix. I took a sample of my saltwater container and the water parameters are as follows:
SG-1.023
ALK-9.6
Calcium-390
Mag-1500

I must have mixed it wrong from the start. I added another cup of salt mix and will test again today.

Thank you for the reply

[jbraslins]

I hope this is not too much of a hijack, but do you guys run carbon/gfo and skim during cycle?

[mchammer]

I didn't run GFO/Carbon until today. and my tank finished cycling a week ago. I did run a skimmer the last two weeks just to break it in.

[bertoni]

You can run carbon and GFO during the cycle, but I suspect that they'd both be exhausted so rapidly that it's not worthwhile. Some water changes likely would be far more useful, depending on the ammonia level and other water quality factors.