Cycling question, can too much ammonia kill my plants? when to add them in?

[Jason]

Hi all,  I'm new to aquaponics, and have just started my first system design.  Im using a 150 stock tank for my (soon to be populated) fish tank, with an 80 gal. stainless steel 90 gal rectangular sink for my raft system/sump tank, with 4 small 25 gal media filled beds to be used primarily as biofilters and a home for worms  that I can hopefully use for a different assortment of crop types.

The water goes from the fish tank, into the media filled beds, then is gravity fed into the ss sink, then gravity fed back into the fish tank.  I'm using blue board for my rafts (I went looking online for any recommendations for raft material, and found some information describing specifically the DOW blueboard is food safe and won't get water logged).

 

So, I tried to begin my cycling about 20 days ago.  I went to the store and purchased what I thought was pure ammonia, added it to my system, then to my chagrin, saw there was soap added.  I had added too much at the time too, so I took that as a perfect opportunity to drain about 120 gallons from the system, and top back up.  I then added organic cold pressed sea kelp extract, and let the system cycle.

Also a newb quesiton, when using the API freshwater testing kit, it says to wait for about 5 minutes to get your ammonia reading, if you wait longer does the reading go higher, or does it stay at the actual reading once reached.  I.e. if I come back in an hour will the reading still be accurate?

for the first week or so, my ammonia readings were (unfortunatly) 8+.  about 5 days ago though, I began to have nitrate then nitrite readings.  Last night my reading were as follows:

 

temp: 64 f

PH 6.8

ammonia 8

Nitrate 45+

Nitrite 5

Can I add plants at this point, or will the ammonia kill them off? 

[TCLynx]

You can probably add plants if they are very hardy.  However, with the ammonia level still so extremely high, you should probably do another few water changes till you get the ammonia reading down to about 4 or less or your cycling may be stalled out (nitrite will keep rising but with the ammonia so high the bacteria that convert nitrite to nitrate will be hindered in their colonization and the nitrite will probably remain really high for far longer than you want.)

Some plants will probably not appreciate the high ammonia level (especially if you are transplanting them and abusing their roots in the process.)

[TCLynx]

oh, and forgetting and leaving the test in the test tube may not be as accurate but if it is turning that really dark 8 + green, your ammonia is just too high and the amount of variation of the shade that might happen after the 5 minutes probably doesn't make much difference anyway.

However, you want to avoid forgetting about the tests and leaving them too long (days) since I've heard some people have had problems with stained test tubes (and those small tubes are tricky to clean.)

[Matt Miskinnis]

I think your ammonia is still a little high, I think you want 4ppm if I remember correctly.  When I started my cycling I had plants in my system from the start.  I figured when the nitrites were being converted to nitrates I would need a way for the nitrates to also go down and the plants would do that.  Also adding some maxicrop helps the plants if no nitrates are present yet.  I just saw that TCLynx commented before me so I am editing my post and will say listen to her.

[TCLynx]

As to the Maxicrop.

That doesn't really provide much nitrogen for the plants.  The maxicrop is to provide more of the trace elements and potassium that are going to be lacking when cycling up with ammonia or simply lacking in most new system start ups.

[Jason]

Hey thanks, I'll head out and do a water change asap, and see how it goes

[Bryan Acred]

Hi Jason,

I would hold off on adding any ammonia until you see it come down to 1ppm or less, then I would add about 2 tablespoons and then check it in 24hrs. The idea is to get your ammonia to where it goes down to almost 0 after dosing 24 hrs prior. Once that is consistent, you are ready to add fish and plants. If you wanted to add plants before cycling has completed, then adding Maxicrop would be recommended for plant nutrition . That's my two cents, but there are a whole lot of smarter folk in here that I know can add more info to this thread. These folks are great and helped me when I started a year ago.

[Jim Troyer]

Hey Jason:

For the soapy ammonia problem, just scoop off the suds.  The soap is on the surface, so it doesn't do any good to remove water from below it, say, with the pump or drain.

Of course, using the correct "pure" ammonia from Ace hardware or a janitorial supply is the way to go.  

I am not saying it is okay to use the soapy variety, but it is a "fix" if you need one.

[Jason]

Thanks Jim, good to know

[Bryan Acred]

I agree with Jim . Ace hardware carries the janitorial strength ammonia. If there is ever a question , just shake the bottle and see if any suds show up. If so, don't buy it.