Pond Boss Forums INTRO Questions & Observations Trout Summer Survival

Set-up:
1/3 acre Northern Michigan Pond
Two 2" wells - total of 30GPM of 50 degree water
Depth average 6 ft.
1/4 dredged to 10-12 ft.
Stocked w/ 200 10-11" rainbow trout on 4/2/06
Auto feeder set to trout chart rate per # / weight
Water temp at bottom, through June = high as 70 degrees
D.O. in May was 14 I believe
Small algae bllom and still many bottom plants in shallower areas (creating O2 during day)
Aerator set to turn on at 60 and off at 63
Water temp on 7/3/06 hit a high of 73 at bottom
Trout are still actve, lively, feeding well

Obviously, as someone wisely put on this site, we are "tip toeing on a ledge in a light wind" with our volume of water etc,

QUESTION - when will the trout begien being stressed and start dieing off???

I've participated in managing a pond for Donaldson strain rainbow trout for a couple of years back in '02 and '03.

One thing that I've learned is that your best friend is good notekeeping. Great job and great report. The reward to anybody helping you is this sort of data accumulation.

Have you decreased the feeding schedule at all as the temp climbs?

Are you feeding highest protein fish chow?

It's exciting that you're doing this and I'm pleased that you are, but don't be surprised if you lose all of them at one time. My impression is that when the first one is about to kick off, he'll swim around real quick and tell the others to drink the Kool-Aid.

Would you please clarify the statement about the aerator turning on and off? I read that to mean that you're only running it within that three degree band. No wait---you're saying that it turns on when temps drop below 60, then back off as they climb back above 63 the following day, right? What have your nighttime temperatures been like lately? I honestly think you can run it a couple more degrees in the morning. Regardless, you don't want your aerator turning on and off during a night when your plants are consuming oxygen. Cecil would know better, but I'd think you're pretty safe up to 65 or 66 degrees.

I can't remember where the diffuser is set within the water column. It's not on the bottom, correct?

Great record keeping as Bruce stated!

I used to work for Aquatic Eco Systems, the world's largest aquaculture supply company and here are a few of my notes from those days:

Consumers of oxygen...

1. Fish
a.) 0.45 lbs of O2/100 lbs of fish/day.
b.) 91 grams of O2/1 lbs of feed fed.

2. BOD (Biochemical Oxygen Demand)

a.) 5.29 grams of O2/KG of Fish @ 1% weight
...one can assume a 70% removal rate
which leaves 30% of BOD to meet.

example: 5.29 g of O2 x 0.3 = 1.587 g
of BOD.

3. Bacteria
a.) 4.25 g of O2/g of ammonia denitrified.
b.) 13.1 grams of ammonia/lb of food fed.

Full example:

10,000 lbs of fish fed 2% body weight/day

a.) Fish requirements
* 10,000 x 2% = 200 lbs of feed
* 200/2.2 = 90.9 kg of feed
* 90.0 x 200 = 18,182 g of O2 required

b.) BOD Requirements
* 90.9 kg x 529= 48,086 g
* 30% x 48,086 = 14,426 g of BOD

c.) Bacteria
* 13.1 g x 200 lbs of food = 2620 g of
ammonia
* 2620 grams of ammonia x 4.25 g of O2
= 11,135 g of ammonia

Total oxygen required = 18,182 + 14,426 + 11,135 = 43,743 g.

43,743/453.6 = 96.4 lbs of O2 per 200 lbs of feed.

So, the question by Bruce of "Have you decreased the feeding schedule at all as the temp climbs?" is so important.

As the temperature increases the oxygen retained in the system decreases. Obviously you are not managing 10,000 lbs of fish but this is an extreme example of some of the things that are going on in under the water.

Thanks guy for the dialogue on this! Important note is I live 2 hours from the pond site, so it's weekends only about every 3rd week, with other brothers going up more frequently to the property.

Answer to previous questions: Yes, we are using a temp controller / thermostat device in "heating" mode so that the aerator starts ON when temp drops to 60 and then turns OFF at 63. So, anything less than 60.

So, according to internet temp records AND real life observation, the temp can drop from 85 in the day to 50 - 60 at night, almost 50% of the time in the June - August season. Important note is that with one well dumping 25 gpm from 3 ft. high into the pond and another artesian putting 7 gpm, there is some decent constant surface splashing 24/7 which I am hoping adds some supplemental and critical night time aeration.

Feeding Answer
I actually "upped" the feeding rate from 1.4% of total body weight (tbw) to 1.7% of tbw this past week. The formula I am using comes form the North Carolina Trout Co-op. 200 rainbows stocked in early April '06 at 10-11", now they are almost 15"! We caught 12 fish. Only ever had evidence of one fish that died, that we could see.

The calculation I am therefore using is:
170 x 1/2 lbs. each = 204 lbs. of total fish
204 lbs x 1/7% @ pond temp of 70-72 = 3.5 lbs feed daily
I have been slightly underfeeding them for the past 2 months with less than 3 lbs. daily. I tested the feed satiation and validated that at about 3.4 lbs daily they stop feeding. Two feed times- 7am, est. 2lbs, and at 9:00pm, est. 1.4lbs. I estimate that I am at or just a hair less than the chart feed rates.

What are your thoughts

Final two answers:
Yes, highest protein 3.5 mm floating trout pellets
(Silver cup brand)

Aerator diffusers (2) spread 1/3 apart are on 1 ft. high pvc frame stands off of bottom at depths about 8 ft.

The concern about aerating more often (especially during direct sunlight hours) is around mixing the water and slight amount of suspended algae (greenish tint) that may reflect the sunlight and absorb the sun more, like a convection oven effect. Should I be worried about this? The water clarity is aobut 3 ft. moderately viewable and not greater than 6 ft. at all viewable.

Anecdotal evidence at my place suggests that there is less waste when using a larger pellet for fish that size. It seems that the littler pellets are more likely to end up drifting to shore and getting caught within shoreline vegetation. Just a thought.

Remember that if you set your benchline "trouble" temp at 70 degrees, then theoretically you should be aerating all of the time at air temps below this to take advantage of the cooling effect.

I'm no salmonid expert, but it seems like you've taken a fairly conservative stance on feeding schedules. Quite a few people out there are feeding more than you--and probably taking a pretty good risk in doing so.

:D

You slay me, Dr. Condello.

Several points:

I gave up on using feeding charts in my ponds early due to the difficulty of capturing fish for sample weights (many floated up dead from the stress a few days later of a quick catch and release) and the variation in growth of my fish.

I think your air temp cutoffs for you diffusers are too low IMHO. Granted your water temps can go up during the day in summer, but it as we all know from basic science it takes a lot of energy to change water temperature.

I turn of my diffuser about 8 or so in the morning and it goes back on at dusk regardless of the air temps.

You are right if you have an algae bloom and some aquatic weeds you are making oxygen during the day. However be aware that a week feric iron solution will mimic the color of an algae bloom. (greenish)

I think you have some colder water than you think. At 70 F. you should be seeing some mortality or morbidity from stress. But again some of your fish may never float to the surface and the ones that do may be carried off by scavengers while you're not there.

If I'm wrong more power to you though.

I'm also feeding only once a day now, and that is in the morning when oxygen levels are rising again after a night of decreasing D.O. levels due to repiration of phytoplankton. Had a very experienced trout farmer tell me to do this -- especially if my water temps are marginal, or my density is high.

I'm losing a few brook trout here and there but I think it's due to the size disparity of the brooks and browns. I'm pretty sure the large browns are chasing them around stressing them out. I've seen it before. Brooks I planted this spring are only 1 1/2 to 2 lbs. while some of the browns approach 5 lbs now even though they maxed out at 2 lbs. when planted in the fall.

Maybe I should stick with browns. My growth rate is astounding for them even compared to my suppliers.

You guys are great- nice dialogue on this. Thank you for your knowledge wisdom and advice! I have been thinking to change to feeding once per day, now I will do it. I recently changed to the smaller 3.5 mm pellet due to a post I say on PB that said smaller pellets allow more fish to feed with less competition etc. Given a once per day feeding that shouldn't be an issue. Time to revert back tot he Silver Cup 5.5 mm floating pellet.

RE: Cecil's assertion that I must have colder temps than 70, I am sure he is right, I just can't seem to find them. I have used several sinking pool thermometers and more recently the AUBE spa/pool/pond digital thermometer on the quest for a truly accurate reading. The AUBE model seemed to be dead on, yet has malfunctioned after only 3 months. I have taken readings from the bottom- tossing it out on a line many times in many areas, but maybe those deep pockets are eluding me.

I actually was swimming in the pond on 7/2 and floated on a inflatable mat over to the new well that is pumping about 30gpm at a mighty cold 50 degrees and I could feel the cooling effect 3-4 ft. under the surface, though I desperatley hoped to get 40+ out of that new well. With only a 2" steel well pipe and a 1 1/4" pvc stuck 20 ft. down inside, it runs out of water when allowed to go full tilt, so I have a restrictor valve on the outlet side so that the flow is constant etc.

RE: dead fish sinking etc., yes most of us would never know. That said, at feeding time, I can estimate there are at least 100-150 in there as there has been massive jumping and splashing activity and they swim in schools around the feeder area for an hour or so before feeding time etc. More later

Mike,

If they are actively feeding that is a good sign and you probably aren't losing any. As long as they are feeding actively you are fine. When fish become sick they feed less or stop feeding just like us.

Here is a trout pond that we have been managing. Our air temps last week were in the upper 80's but the water temp has maintained around 65.

There are several springs feeding this pond and a well that runs through a water wheel for aeration. The largest rainbow caught was 26". Click on this link to see a video of the trout feeding. Photobucket

Cary:
What an awesome backdrop and beautiful pond - wow! Thanks for sharing.

QUESTION - if a 1 1/2" pvc pipe is dropping well water 3-4 ft. into a pond (pond depth of 6-8 ft. below the splashing zone of the pipe) will that aerate it enough. The current thought I have is - with it dropping 3-4 ft. and splashing that it will a) aerate moderately and b) more importantly - push alot of that 50 degree water down to the lower depths and help to maintain a cooler zone down below for protection during the high 80's and 90's we have been haiving in Northern Michigan. What are your thoughts?

Michael,

Now you know why I live in this beatuiful landscape. That view is the same view I get off my front porch!

Any aeration will help. Using the method of a pipe droping the water down 3-4 feet will help. If this water is cooler than the surface, it will sink a little lower than the lighter warmer water. How far can only be determined using a temperature and oxygen meter.

I don't have a formula for that. If you were to run the water through a degassing column you could degass the hydrogen sulfide and ammonia while aerating the water prior to it entering the lake. The column would consist of three pots drilled out in the bottom. Each pot would contain at least 0.6 cubic fee of biomedia.

These pots would be spaced about 6 inches from each other and the top pot would pour into the middle pot which pours into the bottom pot and then into the lake.

With three segments (pots) you could expect an 89% oxygen saturation. Up to five pots, 94% oxygen saturation is possible.

Cary:
That's a heck of a front porch view- very nice, calming and inspiring! Can you tell me more about a de-gassing column, since I've never heard of that???
I had many tropical fish tanks, so I understand about NH2 and NH3 (ammonia) and biomedia for small fish tanks. What is a good low cost biomedia for a 1/3 acre pond? Why would I need to de-gas well water? This well water is heavy mineral water, lots of iron I know, but not sure what else?

Because it is pumped, I can lift it several more feet and then cascade into pots etc. What size pots would hanlde a 25-30 gpm flow?

Here is a link to the web page on the degassing columns. This is a company that I used to work for. Degassing Columns

It is not necessarly the NH3 that is what I was trying to change but increase the O2 by going through those columns.

Michael what you are doing may be just fine. Sounds like you have no low D.O. problems or excess nitrogen problems. Usually well water in our region so low in ammonia I wouldn't even worry about.

The columns are more to increase D.O. saturation as high as possible, and blow off the nitrogen gas and in some waters C02. However, excess nitrogen is really not something to worry about in your pond as there is plenty of room for it to disapate.

What If I send you my D.O. meter which is complete with temp probe accurate to 0.1 degrees. Just promise to send it back when you're done. Then you can let us know what you find out.

Here once again is my packed column which consists of 1 inch plastic media in five gallon buckets.

Great photo Cecil... With the red tint on the buckets, it looks like you have high iron content just like we do here in NC.

If I remember right it's 2.42 mg/l. Larger fish can handle it especially when it settles out in the pond but if I want to hatch my own trout I'll have to remove it.

Very nice pond Cary! Looks postcard perfect.

In the degassing column link you provided, they talk about biomedia. Is this a fancy word for rocks?? Just curious.

Russ,

I'm not Cary, but no, it's not rocks. It's plastic pieces that are hollow inside, have holes etc. that provide a lot of surface area.

As you probably know it can be used to allow bacteria to live on to break down ammonia in recirculating aquaculture systems, but in this case it's to break up the water as it falls, exposes it to oxygen and blows of harmful gases.

Cecil:
That would be awesome if you could loan your D.O. meter. I will be careful with it and send it back insured (2nd day USPS) and list data. My address is
Michael Ebaugh
441 Dorchester Way
Milford, MI 48381

RE: biomedia - I am wondering if standard lava rocks from the landscape supply house would be a good biomedia.

After seeing Cecil's triple bucket brigade photo, I'm going to have to rig up something to maximize D.O.. I like the use of the plastic pails too.

Michael- The idea behind biomedia is to provide the maximum surface area and the greatest possible mix of air and water. This promotes gas exchange and increases oxygen level. The lava rock pores will quickly fill with water and be no more efficient than regular rocks. Here is a link to some expensive bio-balls. You can use any kind of non leaching plastic that has a large surface to air ratio and does not bunch together. This link is for 40 gallons of bio balls just to give you a idea about the most efficient media.

http://www.marinedepot.com/md_viewItem.asp?idproduct=YRB1377

O.K. Mike you got it. Give me a couple days to get it boxed up as I'm a little busy right now. i also need to change the membrane.

Cecil:
Many thanks for your generosity in the up-coming loan. I am cringing with 94 degrees expected in Michigan this weekend! I am hoping and praying for trout survival through the fire of July an August!

Michael in MI