Backyard Aquaponics
A place to discuss aquaponics

Today, it is floating between 99 and 100 at 1PM. Probably will top 100 by 3 or 4 this afternoon. The idiot on the radio says it is great over at the State Fair in Sedalia, about 30 miles east of here, he must be talking about the corn dogs and lemonade!

Kevin

Update.

I've been measuring pH every day, and adding 2-3 teaspoons of calcium hydroxide every day (just like James Rakocy says he does). pH is staying between 6.8 and 7.0. The problems I was having with ammonia spikes have gone away. I show a consistant trace of nitrite, but not enough to worry about. And....here's the cool part....I have been able to increase the feed level from 8 tablespoons (40g) per day to 12 tablespoons (60g) per day!

Nitrates are running 10-20 with the 2 sand columns still in place, but one bed mostly unplanted, and another with just seedlings.The third bed is still a jungle, of course. I currently have no signs of nutrient deficiencies, and have not added any supplements in the past month or so.

Dad came over and pronounced the fish to be officially "eatin' size". He also noted that the remaining fish would grow more quickly once I pulled a few out of the tank. I wonder if those were hints....I'm going to fatten them up a bit more first, though. With the increased rations, they should grow quickly. Yummmmmmm.

Janet,
What do you know about nutrient transfer (or the blocking thereof) due to high ph?

Hi Mathew,
As you infer, I believe that my previous nutrient deficiencies were due, at least in part, to pH out of range. In my case, too low.

I know that somewhere in the 70K posts on the forum, there is a chart of pH and the availability of various nutrients at the different pHs. Nutrients in general are most available between 6.5 and 7.5. Different ones lock out or free up at different pHs. ATM, I can't find the chart. Perhaps someone more organized than I will be able to?

I think that might be why my water hyacinths seem to be starving in what should other wise be very healthy water. Fish wish everyone is happy.

Mathew, as your system matures, your pH will naturally drop. In the mean time, you could add some lemon juice. Make any adjustments to pH slowly and steadily so you don't shock the fish.

how much lemon juice do you figure I need for 15,000 gal.s.? Remember, it's fairly large. What about Sod. Bicarb.? it's a lot cheaper and will do the same won't it?

Sodium Bicarb will move the pH up, not down.

How much lemon juice -- no idea. White vinegar might be cheaper, and I think should work, too. Just start adding a bit at a time and watch pH carefully. However, given the size of your setup, you might be better not to try to adjust things if you don't really have to. Just what is your pH, and how much buffering does your water have?

I don't know how to measure the buffering (I used to and forgot), the ph ranges from 8.3-7.4

8.2right now, everything else is 0

Mathew, I will try to find that pH chart tonight if no one else does me the favor and finds it first. The good thing about running a higher pH is that your bacteria is happier. I'm a little suprised that your pH is swinging that widely. My guess would be that you don't have much buffering, but I also don't know what would be causing such fluctuation. Algae blooms, maybe?

I certainly have lots of happy algea. Thinkink maybe I should try and find a market for it. Another reason for getting some more Tilapia again ( I used to have them, but not currently).

http://www.backyardaquaponics.com/forum ... .php?t=133

is that what your talking about?

Sorry DF, not that one. Good try, though. It was one that looked like this, but I had to go out to the internet to find it again. To save my life, I couldn't find it here...

Mathew, the wider each labeled band is, the more available that nutrient is. For example, Nitrogen is very available from 6.0 to 8.5, but hardly available at the extreme ends of the scale. You are balancing the needs of the plants, the fish, and the bacteria. Many plants would like it at 6.0 - 7.0, the bacteria would prefer 7.0 - 8.0, and fish have different opinions by species. Tilapia will take anything you give them. What I have been seeing is that at 6.0 (maybe lower--my test kit could only go that low), my bacteria was shutting down, resulting in ammonia spikes at the least provocation. I was also seeing what seemed to be general nutrient deficiencies, especially iron. Some of that is just deficiencies in the fish food, but I think some of that was the low pH, too.

There is documentation (with pics) out on the web about what each type of nutrient deficiency looks like. However, it is possible that with 15,000gal of water, you just don't have the fish mass to generate the nitrate you need. You obviously don't have surplus since you are reading 0 on it. One suggestion would be to shade some of the water to reduce the algae. It will consume your nitrates and I forget the whole story, but I know it can cause fluctuations in pH. Adding some floating plants or some rafts might help stablize pH and get the nutrients going where you want.

If you measure pH at the same time of day, do you get the same readings? At different times of day do you get different readings? If yes, then it is the algae causing problems. I would actually work on stablizing the pH swings, see where it truly settles, and then worry about whether you need to add something to correct the pH.

I measured the ph again this morning (I leave the pump off over night, which is mostly for circulation and aeration), this mornings readings are a bit different.

Am. 0+ (something more than 0, but does not quite read .25, the first marking)
Nitrites 0+ (in the right light, it looks like it does not want to be 0, but it still is a ways away from the first mark of .25)
Nitrates clearly 0 but also looks like it wants to change colors
Ph is greatly changed, shows the lowest on the high ph chart (7.4) and the highest on the low ph chart (7.6)

The water is very clear, I can see the bottom of the 5 ft area fairly well, and the fish seem to be very happy, very hungry, however, the plants of all types are NOT.

According to the chart that you show, in this range, the nutrients should still be available, so, it could be lack of NO3 and/or algea stealing it all. I don't really have a means of covering this tank/pool.

??