So if I'm adding 4tsp of KNO3 3 times weekly that means I'm expecting my tank to consume 12 tsp of KN03 each week. Generally speaking that should keep the tank around 15ppm for NO3 and about 10ppm K. The purpose of the 50% water change is to ensure that I never exceed 30ppm if my guess of the tank needing 15ppm is wrong (for NO3 that is - K would be 10ppm and 20ppm respectively).

Is that correct?

Assuming that you have 240 gallons of actual water between your tank and sump (once gravel and stuff is subtracted from the tank volume), if you dosed 12tsp of KNO3 in one week as 3 separate 4tsp dosings, you would have about 42ppm of nitrate in the tank at the end of one week assuming that the plants didn't uptake any of it.

There is no need for this much. When doing 50% weekly water changes, that allows the total amount of nitrate in the tank to reach a level of 2x what you dose each week if the plants never use any of it. That would mean that if your plants never used any of the nitrate, that you would have nitrate levels of up to 84ppm in the tank within several weeks.

If you dosed 4tsp of KNO3 a week total, you would be about right. If you want to dose your ferts 3x a week that would mean doing 3 doses of 1 1/3tsp of KNO3 each. That would put 14ppm of nitrate into the tank over the course of 1 week's time, and if the plants never used any of it the highest the levels would get with 50% water changes is 28ppm assuming that there are no other nitrate inputs into the tank system. That should get you a good starting point for dosing and then try small adjustments if necessary from there as the plants grow in.

I think it is important to start by realizing that you are very unlikely to get an algae problem due to overdosing fertilizers. You are much more likely to get that problem from under dosing CO2 in particular, or any of the other fertilizers. You also have a big tank, which needs a lot of water circulation that occurs in all parts of the tank, in order to keep the nutrients available to all plants all over the tank. Otherwise, even if you dose enough of everything, some plants can still be nutrient limited.

Instead of cutting back on fertilizing I would try to improve the water circulation, try more CO2, and follow the EI dosage amounts until the plants show signs of needing even more nutrients.

Vaughn,

I understand what you are saying. I am working on getting more CO2 in the tank by adding another Mazzei injector to the second return line which will distribute the CO2 more evenly in the tank. With the CO2 mist you can tell there is good flow throughout the tank. The algae is subsiding since I started dosing more KNO3 and less KH2PO4 and backed off the lights (except for a green dusty algae on the logs that looks a lot like Tom's 180 tank which he says is a good thing).

I'm trying to verify if I understand how the amounts Carissa said I should does 3x weekly affects the ppm of the tank over time. It seemed I had it figured out on my last post but Jeremy seems to disagree with Carissa. So I'm still confused. I'm not trying to cause problems just trying to figure this out so I know what I'm doing and why rather than just trusting the experts.

(edit)

I think I get it now - I re-read Carissa's post and she is saying the suggested dose amounts is for a weekly amount. So I want 15-20 ppm of NO3 per week - not each time I dose. That follows then what Jeremy said in stating I would take the 4 tsp and divide by three to get the amount to dose 3x a week (i.e. 1 1/3 tsp). So Jeremy and Carissa are saying the same thing - just different ways.

Thanks,
Aaron

Yep you got er.

Thanks to all for your advice last time but I'm still not quite there yet. The algae has gotten worse. Most of it is staghorn, greenspot on my anubias, thread, and hair algae. I'm still pulling it off but it has gotten so bad that I've had to claim some plants a total loss.

Here is an update on the changes I've made from my original post in this thread.

The tank is now about 2 months old. 180 gallon, 75g sump filter with a Fluval 404 for mechanical/carbon filtration. I've increased the fish load from four SAE, and 10 ottos to 4 SAE, 20 ottos, and 30 Amano Shrimp (many have died as I see translucent carcasses on the gravel each day). I have added 20 cardinal tetras as well and I've been feeding them once daily.

Temp is around 78 F. Lighting has been scaled back to two 95W CF bulbs and two 80W T5 bulbs all 6700K (makes around 2 watts/gal.). The lights are on for 10 hours a day.

The CO2 is probably around 25-30ppm based on the color of the drop checker. The color is a solid green and even yellow green. I don't think it matters but today the pH was around 7.75 in the morning and dropped to 6.5 by 10am - CO2 comes on at 8:30. I'm only using one Mazzei 584 injector with a Mag 9.5 pump driving it (full flow). Another pump - an Iwaki 30 RXT is driving the remaining circulation through the sump.

I'm using the EI method for fertilization. I put in 0..25 tsp of KH2P04 on three days a week. I also dose 1.3 tsp of KNO3 the same days. I am using two capfuls of Seachem Flourish on the following days. I should use four according to the bottle once a week for my water volume.

I've been progressively increasing the CO2 each day hoping to see the algae recede. This because of Tom's advice to others to always suspect CO2. But since I've seen no improvement I'm wondering if I'm missing something (in fact the Staghorn algae is worse where the CO2 water return is).

I've also seen this could be a flow issue so I'm considering adding a Iwaki 30 RT (this is a high head version of the other pump I had running a protein skimmer on my saltwater setup). I was going to attach the Mazzei to this and allow the Mag 9.5 to run unobstructed. Figured maybe this is a flow issue; however, with the two return pumps and the Fluval I'm getting a good 10x turnover per hour so I'm not convinced this is the right approach either.

Sorry for the long post - but I'm trying to give you the complete picture so you can help. Thanks in advance!

Aaron

To make it easier to solve this I suggest turning off one of the T5 bulbs. Those, if they have individual reflectors, are the equivalent of at least 1.5X their wattage when you calculate the watts per gallon. You will have plenty of light with one turned off.

Hi Aaron,

Lowering the light was a good thing for you.


IMO, you are severely underdosing your tank. You are giving the plants lots of light and c02 (maybe), but they are starving for other nutrients. Plus, you are increasing the c02 which is only 1 nutrient (albeit a primary one) that plants need. This causes a need for other nutrients that are just not present in sufficient quantities for the plants to grow well.

However, there are more than enough nutes for the algae to utilize. When the plants are under stress they produce more ammonia which leads to algae. Algae needs less of all nutrients and light to grow, so they can overtake the tank esp when the plants are not growing.

I would do the following:

1. Increase your dosing to 2 tsp of KN03 and 1.5 of KH2P04 DAILY. Dose AFTER the WC.
2. Perform a 50% water change every day (if possible) or every other for a week. This will also help with the algae.
3. Be PATIENT. It will take several weeks for the plants to respond to the abundance of nutrients, esp after being stressed for a time.

Remember that the WC will take care of any excess nutrients if you are concerned about the amount of fertilizers in the tank.

If not better after 1 week, no better growth, less algae, etc, than increase the ferts by 10-25% or some number that you are comfortable with every week until they respond.

After the first week, you can go back to weekly water changes.

I would be very surprised if you don't see some improvement within the first week.

As an FYI, I have a 180 as well and dose daily 3 tsp of K and 2 of P and am still fine tuning

EI is a recommendation, but many folks dose more or less as their tanks need.



Hope this helps.

Thanks for the input Vaughn and Gerry.

I suppose I can try both. I backed off the lighting and corrected the dosing at the same time. And the algae has gotten progressively worse. Gerry, your numbers contradict Carissa's suggestion earlier but I suppose if you are doing it there can be no harm in increasing (I'll proceed slowly though rather than just dosing the same amount you do). From what I've read if I have too much nutrients in the water it doesn't matter as long as I have enough of each (within reason for fish health). It is when a deficiency exists that algae take hold.

I'll try and let you know what happens.

Longahc,

I think you are just looking at the increased dosing that Gerry is recommending and seeing it as just a huge increase in nutrients going into the tank, and you’d be right. Realize that what Gerry is saying related to the nutrient dosing has TWO parts that are both just as important and they are integral to each other. One part is to increase the dosing, and the other part is increasing your water changes to 50% a day (or every other day).

This recommendation is not the same as just increasing your dosing. In reality this dosing regimen in combination with the large increase in water changes doesn’t change your maximum tank nutrient levels from where they are now at all, it just makes sure they don’t run out as easily, and it allows you to help your tank fight the algae by changing out water regularly.

If you just increased your dosing of nitrate for instance, to 2tsp a day (as Gerry is recommending) and kept your water changes at 1x/wk you would be putting 14tsp a week of nitrate in the tank. That would be about 50ppm of nitrate a week, and with no plant uptake, tank levels could get as high as 100ppm within a few weeks. That is not what Gerry is recommending.

Remember that every time you do a 50% water change you are also removing 50% of the nutrients that are in the water from the system. Your total tank levels of nutrients are whatever you dose BETWEEN water changes, and will never reach levels more than double what you put into the tank BETWEEN water changes (when doing a 50% change).

With Gerry’s recommendation of 2tsp of nitrate daily, you are adding 7ppm nitrate to the tank each day, so if you increase your water changes to 50% every day (or every other day) like he is suggesting, you will be adding a maximum of 14ppm of nitrate BETWEEN water changes (if you change 50% every other day). That means, with no plant uptake, your levels would never be more than 28ppm. That is actually exactly the same max nutrient level you have now, so nothing was actually increased at all in that regard.

You have to increase your fertilizing quite a bit when you increase your water changes to compensate for the nutrients that you are removing from the system each time you do a water change.

Now, think along the same lines of Carissa’s earlier explanation with the car and adding gas to see what is actually changing with Gerry’s recommendations:

1- The way you are dosing now is the same as you having a car that starts out the week with 4.6 gallons (4.6ppm nitrate) of fuel. You then add 4.6 gallons more gas two more times during that same week for a total weekly dosing of 13.8 gallons of gas (13.8ppm nitrate). If you get 10mpg in your car, that would allow you to drive a total of 138 miles in one week (4.6 x 3x/wk x 10mpg = total miles). The catch however is that between each fill-up, you can never drive more than 4.6gal x 10mpg = 46mi or you will run out of gas (plants out of nutrients).

2- Dosing the way Gerry is recommending, the car starts out with 7 gallons of fuel on day one. Then you add another 7 gallons on day two. That means that even on day one you have enough gas to drive 7gal x 10mpg = 70 miles if you wanted to. That means that instead of being able to only drive 46 miles each day without running out of gas, you can now drive 70. Then every day (or every other day) you remove half of whatever amount of gas is left in your car and then immediately add another 7 gallons to the tank (same thing as 50% water change with dosing after). So even though the total nutrient levels can still never be more than 28ppm if the plants don’t take up anything at all, you are now able to drive 70 miles a day vs. 46 (like you have with your dosing now). That is your change.

I hope this makes sense. You are increasing the amount of nutrients available to the plants in any one day with Gerry’s recommendations, but you are doing it in a way so that the total levels in the tank still never go any higher than they could with your current dosing. Gerry’s increased dosing is just as safe as the dosing you are doing now in relation to the fish health and maximum levels of nutrients, as long as you take all of the advice he gave you and also do the increased water changes that he is recommending at the same time.

Have a good one, Jeremy