Nutrient Uptake, or lack thereof

The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.

neilanh

Sliced Bread
Joined
Dec 25, 2006
Messages
8,482
Location
Northern Virginia
So my planted tank has been up and running for about a month now. I started originally with DIY CO2, and that just wasn't cutting it, so 10 days ago I made the switch to pressurized and have been running between 30 and 35ppm since.

My question is nutrient uptake. I've been dosing EI with greg watson ferts. But my plants are not taking in any NO3 or PO4. What am I missing? I mix ferts, not dry dose.

Tank specs:
20g high tank
Eco substrate
Pressurized CO2
XP2
temp 76.5° constant
65W dual daylight (6700k/10000k bulb)
kH 5°
gH 5-6°

Saturdays I do 50-60% PWC, afterwards I dose KNO3, KH2PO4, and K2SO4. On Sunday, Tues, Thurs I dose traces (CSM+B)

I've stopped dosing nitrAte and Phosphate at the realization of my levels - however I don't have any faith in my API PO4 test kit honestly. It read 4-5ppm PO4 last night (Mon night, 2 days after PWC and dosing). My Tap water reads 2ppm, and I dosed 1.5ppm on Saturday after the PWC. Before I got the PO4 test kit, I did a week of double dose on the PO4, as I read somewhere a PO4 deficiency could be why NO3 wasn't being consumed. No difference when I did that.

While I'm not convinced on the PO4 levels, I am still concerned with the 0 consumption of nitrAtes. I get 5 from the tap and I dose in 20ppm after PWC. After a week without any additional NO3 dosings, I still read over 20ppm.

Plants:
Bacapa, Microsword, Anubias Nana, Crypts, Wysteria, Hygro, and one or 2 others I forget what they are.

There's no fish in the tank, just snails atm.

I was/am battling a bit of algae. Mainly GSA and hair/thread, although I think the hair/thread is gone. The GSA isn't coming back as much since I went pressurized, but it is still growing slowly.

Lighting is 8 hours a day.

Thoughts?
 
Have you made a nitrate reference solution to verify your testing accuracy?

GSA, has been suggested to be related to low Phosphates. YMMV
 
No, I haven't confirmed the accuracy of it, but it's more the lack of change in it that concerns me. Even if my absolute reading of 20ppm is off by 5ppm or whatever, I should still believe that I should see it decreasing if it's being consumed.

Low phosphates - really? I thought what I had read had it associated with high phosphates. That definately changes my view on several things here, in that both the NO3 and the algae issue could be attributed to that if the PO4 is in fact low.
 
In my experience, once the pressurized (steady) CO2 kicked in, my phosphates dropped by about half in one day. Get a Seachem phosphate test - it's more accurate than the AP test. I was getting colors in my test tube that weren't even on the AP strip. I also like the Seachem nitrite/nitrate test too. I can't really tell the difference between the colors over 30 ppm, but the lower colors are pretty easy to read. Once I got a little more confident of my N and P readings, it was easier to correct my dosing in my 5 gallon tanks, and verified that the EI dosing was working great in my 10 gallon tank.

The Seachem tests come with a reference solution. I use it once in a while, to verify the accuracy of the test reagents and also to "practice" reading the level of a known solution.
 
ALright, so I've got the Seachem Phosphate test, and it's showing near abouts the same. I did the reference solution check, and it was spot on.

So, my tank is right now showing 3+ppm Phosphate, and nitrAtes are 20-30. Using pH/kH, my CO2 right now is steady at 38-45ppm using a calibrated digital meter on the pH.

I still have GSA coming back as well.

what am I missing here?
 
It's possible that not all of the Phosphate registering on your test kit is actually in a form usuable by plants. I'd trust what the GSA is telling you and try dosing a bit more.
 
I'll second Purrbox. I have the AP kit and ALWAYS read well over 3ppm of phosphate but was always having GSA issues and some odd deficiencies. I switched to ignoring the P test kit, and all has been well. I truly believe that several of our kits improperly quantify usable nutrients due to the harsh chemicals used in the test. Several of them use very caustic agents that chemically alter molecules, so you might see "free" phosphate in your test, but are in fact deficient.

Just do as I do. Ignore your test kit for this fert. On water change days dose all of your ferts (iron, potassium, etc.) except phosphate, then the next day dose your phosphate. I do an every other day dosing schedule and have virtually eliminated algae (except that which is due to my DIY CO2).
 
Thanks for the tips guys. I will definately be giving this a try. I guess this planted tank stuff is a lot of trial and error. hehe
 
neilanh said:
Thanks for the tips guys. I will definately be giving this a try. I guess this planted tank stuff is a lot of trial and error. hehe

And its a constantly changing system to boot. After a major trim, rearrangement, fish death, etc. the whole thing needs to be modified. The best you can hope to do is make sure there is enough of everything at all times so you don't over-step the fine line between deficiency and acceptable levels. There's no sure thing!
 
As suggested prior, CO2, CO2 and CO2.

the problem is not the dosing of EI or adding too much/too little, it's not adding enough CO2..........

Adding CO2 drives uptake about 10-25X faster than without.

If you have light and CO2 enrichment, then you should have NO3/PO4 uptake.
If you have poor cO2....which you do..........and you have GSA which is due to either low PO4 or low CO2...............then you can also verify it's poor CO2 or poor PO4.

Add PO4, that rules that out, then you are left with poor CO2................

Fix that, it's all about the gas.

Regards,
Tom Barr
 
Fluctuation in your CO2 and nutrients...as said before...is a leading causation of algae. Standardize lighting and CO2, and be consistient with your dosing regime, and it will clear up.

Are you using Excel as well as gas CO2? How much? How often?

Are you dosing macros any day other than sunday? you should be doing Macro/micro/macro/micro/macro/micro/water change.
 
I understand that CO2 is a driver here, but using the pH/kH method (best I can do right now) my CO2 is reading between 38 and 45ppm. My kH is 5 and my pH during my CO2 period reads between 6.5 and 6.6 using a calibrated digital pH meter. While I'm not opposed to turning it up (at least to the point my new fish can handle), I'm under the impression the target is around 30ppm, and I'm well exceeding that for the past several weeks that I've had the pressurized CO2 system.
 
You live in N VA, that's got limestone and can mess with your KH readings.

You may want to switch to the Drop checker method.

That will address the KH issue.
Folks in OH, IN, KY had 200ppm of CO2, good plant growth, good fish health etc according to the chart, namely due to partial lime softening of the tap etc or other additives they might add to the tap water at the filter plant

Regards,
Tom Barr
 
neilanh,

I've been using the drop checker now for about 4 months and it is REALLY helpful. No more worrying about what your pH and KH say, just properly make up the 4-5 degree KH reference solution and keep an eye on the bulb. You can tell in 2 seconds whether you have an adequate amount of CO2, or whether you need to bump it up more.

I think anyone running on pressurized should have one of these little things. It's slightly more important for us DIY'ers, but to properly dial in the settings I think it would be very helpful to you guys. After all that money spent on the pressurized system, what's another $10-20? :)
 
Back
Top Bottom