Aquatic Plant Forum banner
1 - 16 of 16 Posts

·
Banned
Joined
·
732 Posts
Discussion Starter · #1 ·
OK for those of you who are interested in what happens to K. I received my test kit from LaMotte and did my first test Sunday 7/6. After 10 days doing PPI here are my tank results:

N03: 6 ppm
P04: 0.2 ppm
K: None detected

My plants were showing the effects of low K so I added suficient K to bring my level up to 10 ppm.

Any suggestions on how often you'd like to see tests results?

BTW I'm going to get Fe and CO2 test kits as well.
 

·
Banned
Joined
·
732 Posts
Discussion Starter · #3 ·
Additional details

On 7/6 I checked my water and found that there was no detectable K; so, I added sufficient K to bring the level up to 10 ppm. On 7/8, I rechecked the level and K was at about 8ppm.
I can see a noticeable improvement in plant growth since 7/6 as well as an increase in algae growth.
I add the PPS recommended levels of nutrients daily and replace about 20% - 30% of the water, weekly. I add the equivalent of 20 ppm of CO2 each morning as well as the recommend amount of Flourish Excel.
 

·
Banned
Joined
·
732 Posts
Discussion Starter · #4 ·
update on KPN levels

OK here are the KPN levels after 17 days on PPS

K none detected
PO4 0.2 ppm
NO3 7 ppm

Added K again to bring level to 12 ppm

It appears that after 17 days nutrient consumption is limited by available K.
 

·
Banned
Joined
·
732 Posts
Discussion Starter · #6 ·
Re: update on KPN levels

Not exactly true because K is a mobile element. Plants do take more of K then they actually need so assuming a deficiency from testing K excess is probably misleading.
I agree that K is a mobile element in the fact that it is not incorporated into the structure of the plant and is constantly being exchanged for other K outside the plant. But from my understanding of cellular biology it doesn't seem possible for a plant to take in more K than it needs.

Cellular levels of K must be in a very narrow range for cells to function properly. Plants have biochemical mechanisms that "pump in" and "pump out" K. They can concentrate K from the environment using "pumping in" mechanisms. As the level of cellular K increases, the "pumping out" mechanism starts up. Eventually, the "pumping in" and "pumping out" mechanisms are in balance and the level of K remains constant in the cell.

As long as the plant volume is constant, the level of K in the plants and aquarium water will be the same. As plant volume increases, more K is required and is removed from the tank water.

It may be that my plants have been suffering from a long term deficiency and the amount of K being taken up is just bringing the cellular level back to normal. If that is true then K consumption will eventually decline. I'm interested to see what happens.

BTW. My notion that growth is limited by available K is not unique. There are a large number of aquatic plant fertilizers on the market that supply only K, Fe and trace elements.
 

·
Banned
Joined
·
732 Posts
Discussion Starter · #8 ·
Weekly update:

K 15 ppm
PO3 0.3 ppm
NO3 7 ppm

It looks like the extra K that I added over the last two weeks has finally been incorporated into the plants.

I did an extra 10% water change and will try one or two more during the week.

Over the weekend I made some changes to my tank.
1. Did some aggressive algae control including removal from glass and driftwood.
2. Added 6 more Oto Cats (total of 11)
3. Added 3 Siamese Algae Eaters
4. Added 15 Cardinal Tetras.
 

·
Banned
Joined
·
732 Posts
Discussion Starter · #10 ·
OK here is the weekly update:

K 15 ppm
PO3 0.3ppm
NO3 10 ppm

Here are the details.

Because of visitors, I was unable to do any water changes this week end.

After reading about the toxic effects of gluteraldehyde, I decided to stop using Flourish Excel. Maybe I’ll automate CO2 additions. I have to figure out a way to measure the CO2 added. Anyone have a suggestion.

Subjectively, my tank seems in really great condition although I’m starting to worry about too little algae (yes, I’m worried about starving out my algae eating army).
 

·
Banned
Joined
·
732 Posts
Discussion Starter · #12 ·
I don’t think I can make any solid conclusions. One thing I have learned is that it is hard to determine the levels of chemicals in your water without testing for them.

Once I got my K level up there seemed to be a sharp drop in algae growth. This could also have been due to increased consumption from the added algae eating fish. (This is called a poorly controlled experiment).

My plan is to do additional water changes this week to bring the level of K and NO3 down. I will continue to do the daily additions of macro/micro nutrients.

Since the daily addition of K/PO4/NO3 is approximately 1/.1/1 it seems from the current levels that PO4 is being used more rapidly (in my tank). I’d like to get my tank water to a K/PO4/NO3 level close to 1/.1/1. Then I could get a better grip on how the K/PO4/NO3 level changes with time.

You’ve probably guessed that I have a chemistry background so this has been a lot of fun for me.
 

·
Banned
Joined
·
732 Posts
Discussion Starter · #16 ·
Here is the update for 8/3/08

K 12 ppm
PO4 0.4 ppm
NO3 12 ppm

There is almost no algae in my tank; so, I’ve started to supplement my fish feeding with algae tablets. In the past my Oto’s have ignored them but faced with starvation they may think otherwise.

I’ve changed my fertilization plan temporarily. I’ve stopped using the standard PPS stock solution and started using only a KHPO4 solution that provided the same level of PO4. I’ll continue to do this until I get closer to the stock solution ratios of K/PO4/NO3 = 1.4/0.1/1.

I am doing about 20% water changes per week.

I’ve upped my lighting to max!
I have 2 x 65 watt Sunpaq 6700 K /10,000K CFL on 12 hours/day and
1 x 150 watt Coralife 6700K HQI on 6 hours/day.
The HQI is about 16” above the tank to reduce intensity.

I’m adding 4 gm CO2 daily (equivalent to 20ppm for my tank).
 

·
Banned
Joined
·
732 Posts
Discussion Starter · #17 ·
Tom Barr tells us that the best way to adjust the growth rate in an aquarium is with the light intensity. Next best, is with nitrate, although this is a distant second. His EI method is aimed at always having the tank non-limited by any of the nutrients, and his typical K/PO4/NO3 dosage is more like 1/.25/1 than 1/.1/1. I think he does this because a shortage of phosphate will become the limit on plant growth and that isn't desirable at all.
Everyone has their own formula!

I am using the schedule recommended for PPS:

In 1 liter bottle:
59 grams K2SO4 (Potassium Sulfate)
65 grams KNO3 (Potassium Nitrate)
6 grams KH2PO4 (Mono Potassium Phosphate)
41 grams MgSO4 (Magnesium Sulfate)
Fill with distilled water and shake well. Let sit overnight.

Dose 1 ml of each solution per ten gallons of tank size.

When I chug this through the fertilator I get the following daily increases:

K 1.41 ppm
PO4 0.11 ppm
NO3 1.05 ppm
Mg 0.11 ppm

This agrees with my own spread sheet.

BTW your question about the ratio of PO4 made me go back to my own spread sheet and I found a mistake in my calculations for K2SO4, which I fixed.
 

·
Banned
Joined
·
732 Posts
Discussion Starter · #20 ·
Recently Tom Barr purchased a $1500 instrument that really does measure the concentration of CO2 in the water, independent of pH and KH and other pH affecting substances, accurate to something like +/- 2 ppm, as I recall. He was surprised when he used it to find that he had much less CO2 in his tank water than a drop checker was telling him, and the drop checker gave less CO2 in the water than the pH and KH would tell him. Measuring the concentration of CO2 in water is a very difficult job.
Actually, measuring CO2 in water is an interesting discussion. Do you think we could move it somewhere else where it is more appropiate? I'd add my two cent there.
 

·
Banned
Joined
·
732 Posts
Discussion Starter · #21 ·
Here is the update for 8/10/08:

K 8 ppm
PO4 0.3 ppm
NO3 12 ppm

I couldn't do my usual water change last week so I doubled up on them this week. My TDS is still above where I'd like it to be; so, I'll be doing a few extra changes this week as well.

Next week I'll post a graph with the weekly updates.

This is my feeling so far. NO3 is not much affected by what you put in or take out. I think NO3 may be the result of feeding my fish.

PO4 is pretty much a constant as well. I don't think PO4 is coming from the fish food so it must be from the ferts.

K is definitely very variable and you cannot tell what it will be.
 

·
Banned
Joined
·
732 Posts
Discussion Starter · #22 ·
OK, here are the latest updates on the K level project:

8/15/08
NO3 12 ppm
PO4 0.3 ppm
K 10 ppm

8/25/08
NO3 26 ppm
PO4 0.4 ppm
K 11 ppm


Sorry about the delay but I was away the weekend of 8/16 -8/17 and didn’t get home until late on Monday.
When I left I noticed that my tank was slightly cloudy and when I returned it was pea soup!
I gave it 3 days in the dark and on Friday turned the lights back on to a clear tank. There was some decline in the other plants as well with some dying leaves on the Pigmy Chain and Val.
I installed a UV sterilizer over last week end. My tank is now crystal clear!
Yesterday I checked my water chemistry and was surprised to find that NO3 was so high.
I’d like to think the high NO3 was the cause of my algae bloom but I’m more inclined to believe that the dead algae and plants were the source of the excess NO3.

A chart of the results so far follows.
 

·
Banned
Joined
·
732 Posts
Discussion Starter · #24 ·
Results 8/31/08

NO3 23 ppm
PO4 0.4 ppm
K 10 ppm

I'm going to break away from the PPS Stock plan and go to the NO3 free plan until my NO3 goes down.

If I can figure out how to edit my posts, I'll revise the chart!

I realize that there are people, like Hoppy with green thumbs as long as an arm, who can just smell an aquarium and know what is going on. (That was meant to be a sincere complement). Unfortunately, I can only see numbers and the test result say that for me at least, there is no way to figure out what is going on my your tank with out testing it on a regular basis.

Maybe someday I'll be as good as Hoppy without doing any testing.

BTW: I've almost figured out how to take photos of my aquarium. Unfortunately the colors are all mixed up. When I get that squared away I'll post some pics.
 

·
Banned
Joined
·
732 Posts
Discussion Starter · #26 ·
Here are the results for 9/7/08
NO3 23 ppm
PO4 0.4 ppm
K 9 ppm


My NO3 is still high. I haven't added any additional NO3 in a week. I'm still doing 20% water changes per week.
Tank looks great except for some problems with one Sward plant (see my post in general plant discussions).

If I can figue out how to do it, I should have a picture of my tank in my pictures file.
 

·
Banned
Joined
·
732 Posts
Discussion Starter · #27 ·
Sorry about not posting this last week. I forgot. Here are the results from the last two weeks:

9/14/08

K 10 ppm
NO3 19 ppm
PO4 0.3 ppm



9/21/08

K 8 ppm
NO3 6 ppm
PO4 < 0.1 ppm


There was a dramatic drop in KPN (even though I’ve been adding extra K and P. This appears to be the result of increasing CO2 levels. I added a pH controller and have been gradually lowering the pH (increasing CO2) I’m at 18 ppm now.

My feeling is that I will have to double the PPS rate to keep up with the plant usage at this CO2 level.
 
1 - 16 of 16 Posts
Top